Monster Cookies!! These gnarly looking cookies are a mash up of choc chip, peanut butter and oatmeal cookies They’re crispy on the edges and chewy inside, littered with bright M&M’s and melty chocolate chips, and are as fun to make as they are to eat!

Monster Cookies
I don’t know whether they’re called Monster Cookies because they’re monstrously loaded with goodies or because they’re monstrously ugly in the best possible way. Either way, they’re here today because I ran into last-minute issues with a much more mature recipe I was planning to share.
There was much huffing and puffing about all the time I’d wasted preparing that post, but as they say, every cloud has a silver lining, and these colourful Monster Cookies are what I reached for to lift my grumpy mood. They cheered me up so much, I decided you should get to enjoy them too!
What are Monster Cookies, you ask? I’m glad you did! They’re a mash-up of peanut butter, oatmeal and choc chip cookies, typically chunky, chewy and loaded with M&M’s and choc chips. The name may come from the monster mash-up, though I prefer to think they’re the sort of cookie a Cookie Monster would go mad over!



Ingredients in Monster Cookies
Here’s what you need to make these.
1. For the Monster Cookie Dough
The cookie dough is based on my Brown Butter Oatmeal Choc Chip Cookies (I am very fond of these!), except we aren’t browning the butter here. I didn’t think it was worth it – so many other flavours going on here – peanut butter and so much chocolate!

Peanut butter – This recipe calls for the commercial spread type of peanut butter like Bega (Australia), Jif and Skippy (US) and Sun-Pat (UK) which have sugar, salt and stabilisers added. Yup, the full on commercial sandwich spread stuff! Not the wholesome pure peanut butter which is made with 100% peanut butter, it is thinner and the batter will be too loose.
Oats – Just ordinary rolled oats, not quick cooking oats, not steel cut, and definitely not oats for porridge! Oats gives these cookies a great chewiness and some lovely texture.
Flour – Regular plain / all-purpose flour. Self raising flour won’t work for these cookies, I think they will come out shaped like rock cakes!
Baking soda (bicarbonate soda) – This makes the cookie rise a bit, and also spread. If you use baking powder instead using the standard conversion of 1:3, the cookies bake thicker and the inside is not as chewy, they are a bit more puffy.
Brown sugar – I only use brown sugar in these cookies to give them a lovely caramel-y flavour and make them a nice brown colour.
Egg – A fridge cold large egg, from cartons labelled “large eggs” which are approximately 50-55g/2oz in the shell. Using a fridge cold one helps make the cookie dough stiffer so we don’t need to chill it in the fridge like most cookie doughs, before rolling into balls.
Unsalted butter, melted- The butter is melted so there’s no need to soften it like you often see in cookie recipes. But you do need to cut it into pieces so it melts evenly.
Salt – This brings out the flavours in the cookie, and peanut butter in particular loves salt.
Vanilla extract – Just to add a little bit more flavour into the cookie, complimenting rather than overwhelming the peanut butter flavour.
2. the add-ins
I use M&M and chocolate chips which are classic add-ins for Monster Cookies. And I use a generous amount – 1 1/2 cups in total! Feel free to use whatever you have or want though – think, nuts, dried fruit, peanut or toffee chips. Anything!

M&M’s – Just regular M&M’s, the plain ones without nuts or crispy rice inside. The recipe calls for 1 cup to mix in (200g) plus about 3 tablespoons extra (35g) for pressing on the surface once it comes out of the oven.
Here in Australia we have 180g “snack and share” size bags – if you want to just get one of those, that’s fine, just top up with more chocolate chips, or other add-ins like nuts.
Chocolate chips – I use dark chocolate chips, called semi-sweet chocolate chips in the US. You can use whatever type of chocolate chips you want, or even chop up a block. I use 1/2 cup (90g / 3 oz).
How to make Monster Cookies
This is an easy, hand mixed cookie dough that does not need to be refrigerated before baking. So easy and so fast. How good is that!!

Dry ingredients – Mix the flour, oats, baking soda and salt in a medium bowl, just using a wooden spoon. Then set aside.
Barely melt the butter in a large microwave proof bowl, just microwave in 20 second increments until it is mostly melted but there are still butter lumps. Then finish melting by stirring, using the residual heat. It should be milky yellow, not clear and glassy. This keeps the butter cool so you can continue straight away without chilling the dough before rolling.

Wet ingredients – Add the rest of the Wet ingredients into the butter then mix with the wooden spoon until combined. If there’s a few pesky little peanut butter lumps, that’s more than ok – anyone for little peanut butter pockets in their cookie?? 🎉
Make cookie dough – Pour the Dry ingredients into the Wet ingredients bowl, then mix with the wooden spoon until the flour is mostly incorporated. Then add the chocolate chips and M&M’s (set about 1/4 cup aside for decorating the top of the cookies once baked), and mix until they are dispersed and you can no longer see flour.

Roll cookie balls – Roll the dough into 17 balls*, 3 tablespoons each (4.5cm / 1.8″ diameter), using a size 20 cookie scoop.
Here’s how I do it: scoop/dollop domes onto a tray, continuing until all the cookie dough is used up. Then roll into balls and place onto paper lined trays, 7.5cm / 3″ apart. I put 6 balls on two trays and 5 on the third.
If dough is a bit too sticky to roll, pop the bowl in the fridge for 5 minutes, it will firm up quickly.

Bake 2 trays at a time for 15 minutes at 180°C.350°F (160°C fan-forced), switching the tray shelves so they brown evenly. The edges should be golden and the surface should be light golden. (These cookies are a little more forgiving if cooked longer than they should be, so I encourage you to get some nice colour on the edges, so they go crispy).
Cool 20 minutes – Cool the cookies on the tray for 10 minutes, then transfer to a rack and cool for another 10 minutes before attacking. They will still be warm with melty chocolate, don’t worry! These cookies are a bit more fragile than typical cookies while they are warm, so you want to cool them down a bit more than usual before you enjoy them.
Decorating with extra M&Ms and choc chips
If you want to decorate the top of the cookies with extra M&M’s and choc chips like I have so they are clearly visible rather than half-buried under cookie dough, it must be done while the cookies are hot, fresh out of the oven.
Push the M&M’s in on an angle so they’re halfway embedded, these will adhere in place once the cookie cools. For the choc chips, just place them on top – the heat melts the base so they glue themselves on.

So there you go! A fun cookie that everybody goes mad over, from the under 7s to the over 70s, including a certain French Chef who you’d think would consider brightly coloured M&M-studded gnarly cookies beneath his refined culinary standards, but was caught sneaking cookie after cookie while expertly filleting a fish. 😂
And really, that’s what Monster Cookies are all about. They’re not elegant, they’re not sophisticated, and they certainly won’t win any beauty contests. They’re just big, chunky, chewy, chocolatey, peanut buttery cookies loaded with goodies that make people happy.
I hope they make you happy too! – Nagi x
Monster Cookies FAQ
These were made with gluten-free flour and uncontaminated/pure rolled oats (sold as “wheat free” oats in Australia). The texture inside was the faintest bit powdery while warm (to be honest, it’s so faint I don’t think most people would notice). But once cooled, they were virtually identical to the regular cookies!
However, I can’t guarantee these cookies are 100% gluten-free, for the following reasons:
Oats – Oats naturally do not contain wheat gluten. However, because oats are commonly grown, transported and processed alongside wheat, they can pick up gluten along the way. Produces sold as “pure”, “wheat-free” or “uncontaminated” oats are specially produced to avoid that contamination, like the Red Tractor Wheat Free Rolled Oats I used to make a gluten-free version of these cookies.
However, there is another complication. Under Australian food standards, oats cannot be labelled gluten free because they contain avenin, a protein similar to gluten that some people with coeliac disease react to. So if you have coeliac disease, it’s best to follow the advice of your doctor or dietitian about whether oats are suitable for you.
I haven’t tested an oat-free substitute, though a friend suggested using quinoa flakes instead.
M&M’s – They don’t list gluten-containing ingredients, but the current packaging carries a “may contain gluten, wheat” warning, maybe because they are processed using the same equipment as gluten-containing foods?
If you are concerned, I suggest using something else instead, like nuts or more chocolate chips.
Brand of gluten-free flour – These cookies were tested with White Wings Gluten-Free flour, a brand that is carried by large grocery stores here in Australia. Gluten-free flour blends vary a lot between brands, so I can only vouch for White Wings. However, the fact that it worked so well gives me confidence other good gluten-free flour blends should work too!
4 days in an airtight container in the fridge.
Yes! Roll them into balls and make sure they are kept in a very airtight container or ziplock bag (press out excess air). Then bake straight from the fridge/freezer on demand – no need to thaw! Expect to add a couple of minutes to the baking time.
Watch how to make it
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Monster Cookies
Ingredients
Dry ingredients:
- 1 cup plain flour / all-purpose flour (Note 1 for gluten-free)
- 1 1/2 cups rolled oats (not steel-cut, quick cook or porridge oats)
- 1 tsp baking soda (bi-carbonate soda), sifted if lumpy (Note 2)
- 1/4 tsp cooking salt / kosher salt (halve for table salt, +50% for flakes)
Wet ingredients:
- 125g/ 8 tbsp unsalted butter , cut into chunks (for even melting)
- 3/4 cup creamy peanut butter (not the runny natural, no added salt or sugar kind)
- 1 large egg (~50-55g/2oz in shell), fridge cold is fine
- 1 tsp vanilla extract
- 1 cup (tightly packed) brown sugar
Add-ins (1 1/2 cups of "anything you like):
- 1 cup (200g) M&Ms , plain chocolate ones, not peanut or crispy rice
- 1/2 cup (90g) dark chocolate chips / semi-sweet chips
For pressing on once baked (optional):
- 3 tbsp (35g) M&Ms
- 2 tbsp (20g) dark chocolate chips / semi-sweet chips
Instructions
ABBREVIATED RECIPE
- Mix Dry ingredients in a bowl (with wooden spoon). Barely melt butter, finish melting by hand. Add remaining Wet, mix. Mix in Dry, adding choc chips and M&M's towards the end. Roll 18 x 3 tbsp balls (size 20 cookie scoop), bake 15 min @ 180°C/350°F (160°C fan), cool 10 min on tray then 10 min on rack before attacking!
FULL RECIPE
- Preheat the oven to 180°C/350°F (160°C fan-forced). Line 3 trays with baking paper (parchment paper).
- Dry ingredients – Put the Dry ingredients in a medium bowl and mix with a wooden spoon, just to combine.
- Barely melt butter – Put the butter in a microwave proof bowl and microwave in 20 second increments on high until almost melted. Then mix with a wooden spoon to finish melting using residual heat. (Note 3)
- Wet ingredients – To the butter bowl, add the rest of the Wet ingredients. Then mix vigorously with the wooden spoon until it's smooth.
- Make cookie dough – Add the Dry ingredients in, then mix until most of the flour is mixed in. Then add the chocolate chips and M&M's, then mix until they are dispersed through the batter and you can no longer see flour.
- Roll cookie balls – Roll* into 18 balls, 3 tablespoons each (4.5cm / 1.8" diameter). My method – portion all dough using size 20 cookie scoop, then roll. Place balls on three paper lined trays at least 7.5cm / 3" apart.* If dough is a bit too sticky to roll, pop in fridge for 5 min, firms up quickly.
- Bake 2 trays for 15 minutes, switching the tray shelves at the 8 minute mark.
- Decorate (optional) – While the cookies are still hot, press chocolate chips onto the surface (the heat will melt them enough to stick) and lightly press M&M’s halfway in, they’ll set firmly in place once the cookies cool. (Note 4).
- Cool for 10 minutes on the tray (to finish cooking and set) then transfer to a rack and cool for another 10 minutes before attacking, these cookies are fragile when hot. (Meanwhile, bake the third tray). Fully cool before storing in an airtight container for 5 days, in a cool pantry.
Recipe Notes:
Nutrition Information:
Life of Jaffle
I finally got Jaffle a lovely new bed. Enormous, plush, soft cushiony sofa-like walls, covered in a fluffy blanket complete with a little pillow. Basically a five star puppy hotel bed.

But he still chooses to sleep here:

Seriously. That is his favourite place to sleep, on the cold hard tiles of the shower. Night after night, I put him down on his bed then 2 seconds later he gets up and moves straight into the shower!
The only thing he does with his bed is treat it like a playroom to be destroyed every day.

Most days, the blanket mysteriously disappears off the bed but I know exactly where to find it – he’s not very creative about hiding things he steals from inside the house (and HEY! I spy my crocs!!!):

Getting the blanket back inside and where it belongs is a little harder though because obviously, it is a game! 🤣

There are a lot of people asking about an alternative to peanut butter due to allergies… would almond butter be a suitable alternative?
These look amazing! I’ve got two little grandsons who would LOVE these. I’ve also got a third grandboy but he’s only 8 weeks, a little too young 😄 Will definitely making these, especially for the school holidays. On another note, I made the one pan Mongolian beef noodle dish last Wednesday, using sweet potato noodles. I’m happy to report that they worked very well. I did a double quantity and used 5 packets. It turned out great, and the family loved it. Another make again recipe, thanks Nagi ❤️
I had the same idea as Robyn – try the super-duper bed in the shower and once Jaffle is used to it, place it a metre closer to its designated place every night . . . he’ll have to make up his mind . . . perhaps he really digs the cool slippery feel of the tiles under his tum 🙂 ? Your-cookies-which-came-to-help-the=day resemble my favourite Anzac biscuits just a tad . . . nuts and dark chocolate chips are more ‘me’ methinks than those coloured offerings . . .. . .
Maybe try moving Jaffle’s new bed into the shower at night so he can get used to it?
Can you use something other than peanut butter? My grandson has a peanut allergy.
These look amazing and I need to go buy M&Ms immediately! Is there a sub for the peanut butter for those of us cooking nut-free? Or should I just make the oat cookies and add choc chips and M&Ms?
I wonder if biscoff spread would work?
Oh I’ve never tried that but I’ll have to get some! Thanks for the suggestion!
How about almond butter?
I would love to make these but have nut allergies in our house, can I substitute the peanut butter with anything or not really?
Jaffle likely enjoys the cold tiles.
As for the cookies, I want to know what the others will have. I’ll eat those in one sitting!!
Nagi, I might JUST have bought a large bag of chocolate chips at Costco 2 days ago…and an equally large bucket of M & Ms on spec. I had no idea what I was going to make, but I knew I needed them for SOMETHING! And now, I know why, you enabler you! Your brown butter oatmeal and choc chip cookies are definitely up there in my top 5. I think this may join them. 🤩
By the way, those photos of Jaffle are so adorable. And watch out for the crocs. My Ellie destroyed 2 pair when she was a puppy. She couldn’t eat the $5 thongs – it had to be my crocs…
Yes my grand-dog daughter when not sprinkling her fairy dust golden hair everywhere pinches anything that is left out …I’ve bought tubs now for our clothes when we go to bed 😅 our dog drops his handcuffs though and dobs her in
Nagi, the joy you are getting from Jaffle warms my heart. Dozer will be up there in Dog Heaven with a big smile on his face saying “That was me once-go Jaffle”👏🏻👏🏻❤️
Absolutely 🧡💛
Could these be made without peanut butter? Maybe with biscoff spread instead for someone with a nut allergy?
Jaffle – gorgeous!! I’m thinking, like my lab, it’s because of the coolness of the tiles or flooring as opposed to the warmth of the bed. That’s what I’ve found with our lab anyway. In winter or when cold, it’s a different story and the bed becomes more inviting although not always. Love the bikkies and will try them on the holidays 😊
Can these be made without peanut butter? What would be a suitable substitute? For those with peanut allergies…
Is there an alternative to peanut butter for the cookies, please? They are as they are for my two but my niece has a peanut allergy
Rooooooooh these monsters 😋!!!
I wish my grandchildren were there, they’d love to prepare these ! I preciously keep the recipe 😊👍!!
Jaffle in the shower… like all golden retrievers, he loves water ! Why not schedule some nice and short automatised showers for him … He surely would appreciate, don’t you think 😉😇???
Hi Nagi, Funny how dogs find the odd places to sleep in the house. Cooling mats are helpful when snuggy beds get too warm. Although you may have to disguise it in a pillow case in case Mr Jaffle decides it’s best placed outdoors too with his blanket 🙂 Thanks for the delicious recipes and making everything failproof! A big hit in our house!
My granddog is a Golden Retriever and he too prefers the shower floor, also kitchen floor under a counter. He will never sleep in his cushy dog bed! 🙂