Packed with chocolate chips, M&Ms, and peanut butter, these oat-based cookies are naturally gluten-free.

Theyre 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.

Close-up: monster cookies on a cooling rack with a bowl of M&M’s, and on the counter next to the rack, a monster cookie, and a bowl of chocolate chips with a few on the counter

Simply Recipes / Mihaela Kozaric Sebrek

These are famously kid-pleasers, but who are we kiddingmonster cookies are a combination of everyones 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.

Close-up: monster cookies on a cooling rack with a bowl of M&M’s, and on the counter next to the rack, a monster cookie, a bowl of chocolate chips, some rogue M&M’s on the counter, and a baby blue kitchen towel

Simply Recipes / Mihaela Kozaric Sebrek

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.

Look for no-stir creamy nut butter instead.

Monster cookies on the counter with one cookie bitten into and a small bowl of M&M’s

Simply Recipes / Mihaela Kozaric Sebrek

Need it to be entirely nut-free?

Go for sunflower seed butter.

All of the other ingredients called for are naturally gluten-free.

A plateful of monster cookies with chocolate chips and M&Ms on the side, and a hand reaching in to grab one

Simply Recipes / Mihaela Kozarić Šebrek

Then, transfer them to an airtight container or freezer bag.

Stop the mixer and add both eggs and the vanilla.

Beat for 2 minutes on medium speed.

Two baking trays lined with parchment paper for monster cookie recipe

Simply Recipes / Mihaela Kozaric Sebrek

It will look like a thick paste.

Stop the mixer and scrape down the sides.

Add the baking soda and salt and beat for 30 seconds more.

Butter, brown and white sugar, and peanut butter in a bowl for monster cookie recipe

Simply Recipes / Mihaela Kozaric Sebrek

Add the oats and mix on low speed until fully combined.

Stir by hand with a spatula and combine thoroughly.

Simple Tip!

Ingredients creamed together in a bowl for monster cookie recipe

Simply Recipes / Mihaela Kozaric Sebrek

It can be tricky to get all of the mix-ins to incorporate into the dough.

Just keep mixing and poke any straggling chocolate and candies into the dough balls before baking.

Serve warm or at room temperature.

Vanilla extract and eggs added to bowl with other wet ingredients for monster cookie recipe

Simply Recipes / Mihaela Kozaric Sebrek

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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Bowl of wet ingredients after whisked together for monster cookie recipe

Simply Recipes / Mihaela Kozaric Sebrek

Monster cookie batter in a bowl (without mix-ins)

Simply Recipes / Mihaela Kozaric Sebrek

M&M’s and chocolate chip cookies added to the bowl of monster cookie dough, and next to it, two small bowls (one with chocolate chip, one with M&M’s)

Simply Recipes / Mihaela Kozaric Sebrek

Bowl of monster cookie dough with mix-ins next to two small bowls with more mix-ins (one with chocolate chips, another with M&M’s)

Simply Recipes / Mihaela Kozaric Sebrek

Dollops of monster cookie dough added to a parchment paper lined baking sheet using a cookie scoop, and in the surroundings, the bowl with more monster cookie dough and two small bowls with more mix-ins (one with chocolate chips, the other with M&M’s)

Simply Recipes / Mihaela Kozaric Sebrek

Baked monster cookies on the parchment paper lined baking sheet

Simply Recipes / Mihaela Kozaric Sebrek

Plateful of monster cookies with some on the counter (a cookie with a bite missing also on the counter) next to a bowl of chocolate chips and a bowl of M&M’s

Simply Recipes / Mihaela Kozaric Sebrek