These gluten free monster cookies are the perfect easy treat! They're full of all the classic ingredients including peanut butter, oats, chocolate, and M&Ms just minus the flour!

Why you need these flourless monster cookies
I honestly think these may be my new favourite cookie. They have everything I love in a cookie.
- They are flourless! These aren't any regular cookie these are FLOURLESS monster cookies! It's basically like eating oatmeal for breakfast (except slightly different haha!). I love using oat "flour" in cookies for an added fibre boost!
- They have fun mix-ins. This is your chance to get creative! Seriously. Add whatever toppings you heart desired to these chewy monster cookies (the edible eyeballs are a can't miss in my opinion).
- They're slightly lower sugar and lower saturated fat than your typical cookie. Although there is nothing wrong with a good cookie sometimes you just want a slightly more nutritious version. These are the perfect afterschool sweet snack kids will love!
- They are SO easy to make. Seriously whenever you get a sweet craving RUN and make these you won't regret it.
Ingredients needed for peanut butter oatmeal m&m cookies
Oats- Oats are the basis of a good monster cookie. Quick, minute or rolled oats all work!
Oat flour- To make these flourless monster cookies we use oat 'flour' which is essentially just blended oats! You can buy this pre-made or make your own in under 2 minutes at home (I go into how to do this below). I have not personally tried using all purpose flour or almond flour however if you try let me know how it turns out!
Vanilla extract- For flavour! As we are baking these cookies there is really no difference between using artificial vanilla extract or real vanilla extract ( so I recommend going for the cheaper option)!
Brown sugar- ½ cup of brown sugar is all the sweetness this recipe needs! For slightly sweeter cookies, feel free to use ⅓ cup. Coconut sugar also works perfectly in these.
Peanut butter- I use natural peanut butter in all of my recipes as I like to add my own sweetness to recipes! Look for a peanut butter that is made with only 1 or 2 ingredients: peanuts, and salt (optional).
Butter- To help create the PERFECT texture. For best results, I recommend using room temperature butter,
Mix-ins- this is up to you! I like to use chocolate chips, m&ms and edible eyeballs in mine! I go over some more recommendations below!
How to make chewy monster cookies
These are the perfect 'throw together' cookie when you're craving something sweet but don't feel like making a complicated recipe. That's because these are INCREDIBLY easy. Gather your ingredients, grab two large mixing bowls and a cookie sheet and let's go!
Step one: Cream together your peanut butter, brown sugar and butter. I personally recommend using a handheld electric mixer or stand mixer for this step. I know it involves slightly more clean up but I promise it's worth it. The longer you beat together the sugar with the butter (and peanut butter) the chewier your cookie will be (I typically recommend 3-5 minutes). Once your done, add in the egg and vanilla extract and mix again.
Step two: Time for the dry ingredients. In a separate mixing bowl, combine your oat flour, oats, salt and baking soda. For your oat flour you ave two options, you can either buy pre-made oat flour (I like this one) OR you can make your own at home. I typically go fo the second option as oat flour is EXPENSIVE and it's so easy to make.
Step 3: Combine your wet and dry ingredients. Add your dry ingredients into the bowl your wet ingredients are in and stir using a spatula or wooden spoon. Add in your mix-ins and mix again.
Step 4: Bake! Roll out your dough (I use about 2 tablespoons of dough in each cookie- recipe makes 10 cookies) and drop onto a prepared baking tray. Gently press each dough ball down using the palm of your hand until the cookies are about ½-1/4 inch thick. Press in additional toppings if desired and bake for about 12 minutes.
Make your own oat flour: in a food processor or high powered blender ( I like using my Magic Bullet for this) add ¼ cup more oats to a blender than you need (ie. 1 cup of oats = ¾ cup oat flour) and blend until a smooth flour-like powder forms!
The perfect healthy Halloween cookies
I don't know how we got this far without covering the basics! Why are these peanut butter oatmeal m&m cookies called monster cookies? and why do they make the perfect healthy Halloween cookies?
These cookies are called monster cookies because they are the 'Frankenstein monster' of the cookie world. They are the perfect mash-up of all of our favourite cookie recipes. You have part oatmeal cookie, part peanut butter cookie, and part classic chocolate chip. Does it get better than that? I THINK NOT. PLUS they add a very unique spin by using m&ms as a fun, colourful mix-in!
To make these the perfect healthy Halloween cookies mix in some spooky candy. Right before baking I pressed some edible candy eyes into each cookie to create the spookiest (really the cutest) monster cookies ever! I found my edible eyes at Real Canadian Superstore in Canada, however I have also seen them at Walmart and on Amazon. OR you can make your own by adding a dot of melted dark chocolate to the bottom of white chocolate chips.
Other great options include:
- Reeses Pieces
- Pretzel pieces
- Candy corn
- Reeses cups pieces
- Any spooky Halloween candy you can find!
Frequently asked questions
Can I make the dough ahead of time and freeze it?
Yes! All you have to do is make your cookie dough balls, place them on a baking sheet and freeze. Once the cookie dough is frozen, pop them in a large airtight freezer bag and store in the freezer. The only difference is when you bake them you will likely need to bake for between 2-5 minutes more than stated in the recipe. Additionally, as these cookies don't spread too much on their own you will need to gently press down on them after they are baked!
How should I store these chewy monster cookies?
These cookies store perfectly on the counter in an airtight container for up to 7 days. If you want to store them for longer they also freeze great!
Can I make these cookies vegan?
You can! Simply replace the butter with coconut oil and swap the egg for a flax egg (combine 1 tablespoon of ground flaxseed with 3 tbs of water). Just make sure all of your mix-ins are vegan as well!
I have a peanut allergy! Can I substitute the peanut butter for anything else?
I have not personally tried! A classic monster cookie does contain peanut butter so while creating this flourless monster cookie recipe I wanted to stick as close to the classic version as possible! I would say that using sunflower seed butter or even coconut oil *should* work. However once again, I just can't say for sure!
More easy sweet treats
If you loved these flourless monster cookies you need to try some of my other favourite sweet treats:
- chai spiced oatmeal cookies
- sweet potato brownies
- salted caramel blondies
- gluten free sugar cookies
- lemon thumbprint cookie
PS. I love seeing my recipes in action! If you decide to make these gluten free monster cookies don't forget to tag me on Instagram - @nourishedbynic or leave a comment below!
📖 Recipe
Gluten Free Monster Cookies
Ingredients
- ½ cup brown sugar
- ¼ cup natural peanut butter
- 2 tablespoon butter room temperature
- 1 large egg
- 1 teaspoon vanilla extract
- 1 cup oats quick, minute or rolled all work
- ¾ cup oat flour
- ½ teaspoon baking soda
- ½ teaspoon salt
- â…“ cup M&Ms
- â…“ cup chocolate chips
- 10 small candy eyeballs optional
Instructions
- Preheat oven to 350°F and line a baking tray with parchment paper.
- In a large mixing bowl cream together brown sugar, peanut butter and butter until smooth (about 3-5 minutes). Add in egg and vanilla extract and beat until smooth.
- In a separate bowl mix together oats, oat flour, baking soda, and salt.
- Create your dough by slowly adding your dry ingredients to your wet ingredients. Mix together using a spatula or wooden spoon until fully combined. Add in your mix-ins (chocolate chips and M&Ms) and stir again. Roll dough into 10 balls (using about 2 tablespoons of dough in each), arrange on the cookie sheet and gently press down using the palm of your hand (until between ¼-1/2 inch thick), press in additional toppings (ie. candy eyeballs) and bake for about 12 minutes.