Monster cookies are soft-baked, peanut butter-based cookies loaded up with oats, chocolate chips, and M&Ms. They’re crisp on the outside and soft and chewy on the inside. This version is flourless, relying on peanut butter and oats to create an irresistible texture.
These are famously kid-pleasers, but who are we kidding—monster cookies are a combination of everyone’s favorite things.
What Oats to Use for Monster Cookies
This recipe requires quick-cooking oats. Because the cookies are flourless, the finer texture of quick-cooking oats is critical for binding everything together. If you only have old-fashioned oats on hand, pulse them a few times in a food processor to break them down so they resemble the quick-cooking variety.
A Note on Nut Butter
Creamy peanut butter is the classic base for monster cookies. While chunky will work too, it adds a significant crunch to each bite. If you’re avoiding peanuts for an allergy, or just want to try something new, almond butter makes a delicious swap. Note that the cookies made with almond butter will be flatter, but will still have their signature chewy middles.
In any case, be sure your nut butter is completely emulsified. Natural nut butters, made of just nuts and salt with the oil separated, are not recommended. Look for no-stir creamy nut butter instead. Need it to be entirely nut-free? Go for sunflower seed butter.
Mixing Up the Mix-Ins
It’s not a monster cookie without M&Ms and chocolate chips, but you can always put your own twist on it! There are countless flavors of M&Ms to try, plus other candies like Reese’s Pieces, Heath Bar bits, and more.
The chocolate chips can be semi-sweet like we’re using here, or they can be milk or dark chocolate depending on how sweet you’d like your cookies. Chopped nuts, like pecans, would be a great addition, or toss in some raisins for a bit of chew.
While oats do not contain gluten, they may come in contact with grains that do during their production and processing. If you want to ensure these cookies are completely gluten-free, be sure to use oats that are labeled as gluten-free. All of the other ingredients called for are naturally gluten-free.
How to Store and Freeze Monster Cookies
Store baked monster cookies in an airtight container at room temperature and they will stay fresh for 3 to 5 days. To freeze, place completely cooled cookies in an airtight container or freezer bag and they’ll keep in the freezer for up to 2 months. When ready to enjoy them, thaw them at room temperature or heat them in the microwave for about 30 seconds.
Raw cookie dough can be stored in the fridge for up to 3 days before baking and up to 2 months in the freezer. To freeze, portion the dough into balls, top with the M&Ms and chocolate chips, and freeze them in a single layer. Then, transfer them to an airtight container or freezer bag. When ready to bake, do so from frozen and simply add a couple of minutes to the baking time.
Peanut Butter Treats
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Preheat the oven to 350°F.
Line two baking sheets with parchment paper or silicone baking mats.
Cream the peanut butter, butter, and sugars:
In a large bowl or stand mixer, cream together the peanut butter, butter, brown sugar, and granulated sugar on medium speed for 2 minutes, scraping down the sides halfway through.
Add the eggs and vanilla:
Stop the mixer and add both eggs and the vanilla. Beat for 2 minutes on medium speed. It will look like a thick paste.
Add the dry ingredients and mix-ins:
Stop the mixer and scrape down the sides. Add the baking soda and salt and beat for 30 seconds more.
Add the oats and mix on low speed until fully combined.
Reserve 2 tablespoons each of the M&Ms and chocolate chips and add the remainder to the oat mixture. Stir by hand with a spatula and combine thoroughly.
Scoop and bake:
Use a heaping medium cookie scoop or spoon to portion the dough into 1 1/2-inch balls (for a total of 22 or so balls) and place them at least 2 inches apart on the prepared baking sheets. Then, using your hands, roll them into uniform balls and press the reserved M&Ms and chocolate chips onto the tops of each cookie dough ball.
Bake until the edges are just starting to turn golden brown, 12 to 16 minutes, rotating the pans halfway.
Cool and serve:
Let cookies rest on the baking sheet for 5 minutes before using a spatula to transfer them to a wire rack to cool. Serve warm or at room temperature.
Once the cookies have cooled completely, store them in an airtight container for 3 to 5 days. They can also be frozen for up to 2 months.
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