These Thick and Chewy Monster Cookies are loaded with peanut butter, oats, M&M's and chocolate chips. They’re a cross between a chewy oatmeal chocolate chip cookie, and a peanut butter cookie, and they’re sure to be a huge hit with family and friends.

I LOVE making cookies, and since I don't usually have fresh-baked cookies available on the spot, I like to freeze them for when friends come over or when we just want a little treat.  In my freezer currently are Jumbo Chocolate Chip Cookies, Red Velvet Sandwich Cookies, and Chewy Pumpkin Chocolate Chip Cookies.  Who wants to come over?!

Monster cookies with m&m's on a wire cooling rack.

Monster Cookies

Don't ask me to choose a favorite type of cookie because I just wouldn't be able to! There are too many fun variations. These Monster Cookies are always popular and I love the great texture from the oats and the subtle peanut butter flavor.

Why are they called Monster Cookies?

There’s not an exact answer for why these cookies are called “Monster” Cookies. Some people think it’s because they look like monsters, with their bumpy texture and fun colors. I like to think it’s because they’re stuffed with so much “stuff”, making them the “monster” of all cookies.

Whatever the reason, all Monster Cookies have these ingredients in common: peanut butter, oats, chocolate chips and m&m chocolate candy.

The ingredients for monster cookies including a measuring cup with peanut butter, a small bowl of rolled oats, and a pile of chocolate chips and m&m's.
How to make Monster Cookies:
  • Cream the butter and sugars. Use REAL butter and cream it with the sugar for at least 2-3 minutes until really light and fluffy. This is adding air to the mixture and is the base for the texture we want in our cookies.
  • Mix wet ingredients. Add the peanut butter and mix well. Add egg and vanilla and mix.
  • Measure flour properly and mix dry ingredients. When measuring the flour be sure to fluff it a bit first, allowing air to fill in (like sifting) before you spoon it lightly into the measuring cup. Stir together the flour, oats, salt, baking powder and baking soda. Stir into wet mixture with m&m's and chocolate chips.
  • Slightly under-bake. Bake at 350, being careful not to over bake the monster cookies. The tops will look just set and they will continue to harden and set up as they cool on the baking sheet.

A bowl full of the dough for monster cookies next to another photo of the cookies rolled into balls on a baking sheet.

How do I keep my cookies from spreading?

During baking, cookies naturally spread, but the key is to make sure they don't spread too much.  To keep your monster cookies from spreading, be sure to use exact measurements (no guesstimating) and use room temperature ingredients, particularly the butter and eggs.  You can also stop cookies from getting flat by chilling the dough for 15-30 minutes before baking.

Storage and Freezing Instructions:

These cookies will keep well in an air-tight container for 1-2 days, or you can freeze the cookie dough or baked cookies. To freeze them after they’re baked, allow them to cool completely and store them in a freezer safe container for up to 3 months. Freeze cookie dough balls in a freezer safe container and when ready to bake, place the frozen cookie dough on a baking sheet and add 2-4 minutes to the baking time.

Monster cookie on a marble board with a bite taken out of it.
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Recipe

Monster cookies with m&m's on a wire cooling rack.
Prep 15 minutes
Cook 10 minutes
Total 25 minutes
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Ingredients
  

Instructions
 

  • Preheat oven to 350 degrees F.
  • Cream the butter and sugar together really well—at least 2-3 minutes until light and fluffy.
  • Add peanut butter and mix well. Add egg and vanilla and mix.
  • In a separate mixing bowl stir together the flour (be careful to measure correctly, spooning the flour into a measuring cup, then leveling off), oats, salt, baking powder and baking soda.
  • Add to the wet mixture and mix to combine. Stir in chocolate chips and M&M’s.
  • Bake at 350 degrees for 10-12 minutes, or a little longer if you make them bigger than a 1 inch cookie scoop. Don't over bake--they will look just set. 
  • Remove them from the oven and allow them to cool completely on the pan.

Notes

Adapted from our Mrs. Fields chocolate chip cookie recipe.

Nutrition

Calories: 191kcalCarbohydrates: 23gProtein: 3gFat: 9gSaturated Fat: 4gCholesterol: 18mgSodium: 114mgPotassium: 94mgFiber: 1gSugar: 14gVitamin A: 145IUCalcium: 25mgIron: 0.9mg

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About The Author

Lauren Allen

Welcome! I’m Lauren, a mom of four and lover of good food. Here you’ll find easy recipes and weeknight meal ideas made with real ingredients, with step-by-step photos and videos.

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ryley dickamnn
1 month ago

5 stars
OMG, these cookies are to die for. 10/10 would recommend. the only part I regret is eating them all. haha 😅

Krystal
6 months ago

5 stars
I should have never made these cookies because they are so so delicious and I will eat them all!!

Jasmine
7 months ago

5 stars
Every year I do a “bake off” where I try several recipes of the same type of cookie. This year was monster cookies, and this came out the winner! Best of the top four recipes on the internet. Thanks for sharing!

Samantha Boyd
11 months ago

5 stars
BEST MONSTER COOKIES EVER! They’re crisp on the outside and chewy on the inside. We used the pack of M&M’s with peanut, peanut butter, and regular in it and it was a great choice.

Kennadi
1 year ago

I love monster cookies so much and these are delicious. Nice and chewy they don’t get hard if they sit out or in the fridge. They’re literally perfect.

Bekah
3 years ago

5 stars
I have made this recipe so many times and decided it was time to comment. These are the best monster cookies. thank you. we make them all the time.

Shawna
3 years ago

I make these with gluten free flour and they are so good.

Mary Allen
3 years ago

Great to find recipes when you need them

Heather
3 years ago

1 star
Do you keep the dough in a ball or do you press it down before baking? The recipe doesn’t say. I made these and just left it in a ball but then these didn’t look done after 11 minutes. They fall apart and I kept putting them back in the oven to finish cooking them. They just don’t look like they set up at all. Super disappointed ☹️

Patricia
3 years ago

5 stars
I am making Christmas cookies and these are a must have. They turned out so good. This is definitely a recipe I will make again.

Rebecca Young
3 years ago

5 stars
Yummmmmmmmmmmmmmm! So simple and so freaking delishhhhhhh

Erin
3 years ago

I really like monster cookies, but I have never made them before tonight. I wasn’t a huge fan. I thought they were too sweet, and not peanut buttery enough. Could have also used more salt. My cookies turned out like balls, they didn’t spread at all. The recipe didn’t really indicate how to form the cookies–was I supposed to flatten them? Maybe I did something wrong? I don’t know. I would not make this recipe again. Disappointed.

Heidi
3 years ago

5 stars
love this recipe.. so hard not to keep eating these cookies. I am a stay at home mom and logging wife i am always looking for that good recipe. this is it!

Shannon
3 years ago

5 stars
I love these cookies! This has become my go-to recipe since they’re so yummy and more fun than just plain chocolate chip. 🙂

Toni Modaffari from Lake Placid Florida
3 years ago

4 stars
Delicious cookies

Kerry
3 years ago

5 stars
I’ve made these for the men’s softball team I help coach and now they ask for them at every tournament. With 4 back to back championship wins, it’s needless to say that I am making these today for their tournament this weekend as well. I put them in a plastic shoebox container lined with parchment paper (one for each day of the tournament) and they stay soft all weekend! Thank you for the delicious recipe!!