The Best Monster Cookies

These soft, thick, and chewy monster cookies are about to become your favorite cookie! Loaded with peanut butter, quick oats, chocolate chips and m&m's, these have all that sweet & salty flavor with the perfect chewy texture!

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Why I Love These Monster Cookies

Thick & chewy: The addition of the quick oats makes these a hearty, thick cookie that you'll love! These are truly the best monster cookie recipe I've made!
Sweet & salty: Between the peanut butter and candy mix-ins, these monster cookies are the perfect mix of sweet and salty.
Easy to make! While you do need a mixer to whip these up, these are quick to make in one bowl!

Ingredient Notes

This is just an overview, click here to jump down to the full recipe card for the recipe amounts and condensed recipe instructions.

Creamy peanut butter: For this recipe, I highly suggest using creamy peanut butter like Jif or Skippy. Natural peanut butter has more oil and will not bake the same.
Quick oats: These are found in a large cylinder container in the cereal aisle and are different than "rolled oats" in that they're smaller, less chewy, and will bake up quicker. If you only have rolled oats, feel free to substitute for a chewier cookie.
Unsalted Butter: I personally bake with unsalted butter so that I can control the salt but salted butter will work fine in these cookies; just omit the additional salt!
Mix-ins: I do a mix of semi-sweet chocolate chips and m&m's but feel free to toss in any candy you'd like!

Make it gluten-free! Use your favorite gluten-free oats and flour to make this gluten-free! My favorite brand is Bob's Red Mill Gluten Free 1-to-1 Baking Flour.

How to Make Monster Cookies:

This is just an overview showing step-by-step photos, click here to jump down to full recipe card with exact instructions.

Step 1: Mix Dough

In a large bowl, use an electric mixer on medium-high speed to cream softened unsalted butter (½ cup, 1 stick), light brown sugar (½ cup), and granulated sugar (¾ cup) for 1-2 minutes.
Add in creamy peanut butter (1 cup) and mix until incorporated.
Add the eggs (2 large) and vanilla extract (2 teaspoons) and mix on low speed until combined.
Add in baking soda (1 teaspoon) and salt (½ teaspoon) and mix for another 5-10 seconds until combined.
Add quick oats (1 ½ cups) and all-purpose flour (1 ¼ cups) and mix on medium until combined.
Add in semi-sweet chocolate chips (1 cup) and m&m's (1 cup) and mix until just combined.

Tip: You may need to stop the mixer & scrape down the sides to incorporate all ingredients.

bowl of monster cookie dough with chocolate chips and m&m's

Step 2: Scoop & Flatten

Scoop dough into ¼ cup (4 tablespoons) sized scoops (I use this stainless steel cookie scoop!), roll into balls, tehn gently flatten each dough ball into a ½" thick disc; this will also help them spread instead of be puffy.

Tip: Press extra m&m's on top of each cookie for a pretty presentation.

Step 3: Bake

Bake at 350°F for 10-12 minutes. Do not overbake. The cookies will continue to bake on the hot pan, allowing them to firm up without overbaking.

Allow to cool, then enjoy! It's important for them to cool; they will be fragile while they're warm.

Frequently Asked Questions

What are monster cookies made of?

Monster cookies are a combination of peanut butter, oats, chocolate chips, and m&m's! They are the ultimate cookie with the perfect chewy texture and sweet & salty flavor! You can also mix-in white chocolate chips, butterscotch chips, chopped peanuts, and other chopped candy!

Can I freeze monster cookie dough?

Yes you can! Scoop the dough, roll, and slightly flatten then store in an airtight Ziploc bag for up to 3 months. When ready to bake, place on baking sheet and let thaw for 30 minutes or bake from frozen for an extra 2-4 minutes (times may vary with your oven).