Enjoy easy to make Monster Cookies. A classic thick cookie with a crisp edge and soft center, loaded with peanut butter, chocolate, oats, and M&M’s, creating sweet moments for all.

Peanut butter cookies are always a reader’s favorite cookie recipe, including Peanut Butter Chocolate Chip Cake Mix Cookies, Rice Krispy Peanut Butter Balls, Peanut Butter Cup Cookies, and  Reese’s Pieces Peanut Butter Cookies.

Be sure to sign up for my email… to get new recipes and ideas in your inbox!

m&m monster cookies on a table, one has a bite missing

Why You’ll Love Monster Cookies

If you love cookies with lots of mix-ins, you’re in for a treat with these thick and chewy cookies.

  • Fun, Whimsical, Crowd-Pleasing – These cookies are bursting with the delicious combination of peanut butter, chocolate chips, and M&M’s.
  • Soft and Chewy Texture – Monster Cookies are known for their delightful soft and chewy consistency that’s incredibly satisfying.
  • Customizable, Easy Monster Cookie Recipe – They’re perfect for customizing with your favorite mix-ins, from nuts to coconut, making each batch unique.
  • Cookie Baking With Kids – The dough is easy to handle, and kids will love picking out and adding their favorite mix-ins.
  • Pantry Tidy Up – A great way to use up leftover ingredients like a half-empty bag of M&M’s, chocolate chips, or other baking supplies, this monster cookie recipe is a great option.
  • Holiday Monster Cookies – With color-themed M&M’s, you can easily create festive cookies for any occasion, such as Halloween, Valentine’s Day, or Christmas M&M monster cookies.
ingredients for monster cookies on a counter with a red towel

What You’ll Need

For specific amounts, please refer to the printable recipe card at the bottom of the post.

  • Salted Butter – softened should be soft enough to cream together easily with the peanut butter and sugar, but not so soft that it’s melted.
  • Creamy Peanut Butter – Use your favorite brand of creamy peanut butter. Crunchy peanut butter will also work, but it changes the dough’s texture and cohesiveness.
  • Sugar – adds sweetness and helps the cookies to brown.
  • Brown Sugar – light brown sugar adds moisture and notes of molasses flavor to the cookies. Brown sugar gives the cookies a deeper flavor and chewier texture.
  • Large Eggs – room temperature eggs will mix into the batter more easily and help to produce a chewier cookie.
  • Vanilla – provides a soft, balancing aroma and helps to enhance the other flavors in the cookies.
  • All-Purpose Flour – if you haven’t made your flour measurement failproof with a kitchen scale yet, use the fluff, spoon, and level method for the best monster cookies!
  • Baking Soda – is a leavening agent that gives the cookies lift.     
  • Salt 
  • Old-Fashioned Rolled Oats – a classic monster cookie mix-in. They add sweetness, richness, and chocolatey flavor.   
  • M&M’s – the signature monster cookie recipe add-in. Chocolatey candy-coated morsels provide color and a delightful crackle. 
  • Semi-Sweet Chocolate Chips – another classic monster cookie mix-in, second to M&M’s, that adds creamy chocolate richness.

To test baking soda, place a few tablespoons of vinegar in a small dish and stir in about a teaspoon of baking soda. The mixture should immediately begin to fizz if the baking soda is still active; if there’s little to no reaction, it’s time to replace it.

This post may contain affiliate links. Please read my disclosure policy here.

How To Make Monster Cookies

This soft and chewy cookie recipe is simple and always provides delicious results. So, grab a large bowl, electric mixer, cookie scoop, and spatula. Then line two half baking sheets with parchment paper, set the oven to 350° F, and we are ready to get started.

cookie scoop

Featured Product Cookie Scoop

Perfect for creating beautifully rounded balls of cookie dough, ice cream, meatballs, cupcakes, melon balls, and more.

When you are making this recipe, you’ll want to use the full recipe at the bottom of the page.

  1. Cream butter and peanut butter, then add sugars until light and fluffy. Add vanilla and eggs, salt, baking soda, and flour until just incorporated.
  2. Add the oats, M&M’s, and chocolate chips and mix by hand. 
  3. Using a cookie scoop, place cookie dough balls onto lined baking sheets.
  4. Bake 8-9 minutes until edges are lightly golden and cookies are puffed. 
  5. Lightly push several M&M’s and chocolate chips onto the hot cookies. 
  6. Transfer monster cookies to a wire rack after sitting 3-4 minutes on the baking sheet.
  7. Treat yourself and your special someone to a cold glass of milk and a warm monster cookie!

My husband especially loves to eat freshly baked monster cookies warm out of the oven! They are a huge favorite with our family and friends.

How To Measure Flour Properly: Did you know THE WAY you measure flour matters? The most precise way to measure your flour is by weight using a digital kitchen scale. 1 cup of flour weighs 125 to 130 grams. If you don’t have a scale measure your flour by scooping flour with a spoon into the cup. Don’t use your measuring cup as a scoop, as it packs the flour down and gives a different measure.

2 giant bakery style monster cookies with M&M's

Recipe Notes And Tips

  • Nothing beats a lightly sprayed 3 tbs cookie scoop to get uniformly sized cookies, or you can use a kitchen scale for 2.5-ounce dough balls.
  • Keep monster cookie balls with a few inches between them; even though they don’t spread much, they need their room. (I usually get 6 cookies on my half-sheet pans).
  • When decorating cookies with additional M&M’s and chocolate chips, the cookies must be hot enough for the extras to stick. 
  • For the ultimate monster cookies, like those you see in a bakery shop, shape the cookie dough into uniformly sized 4-ounce cookie balls so they bake evenly. 
  • I like to use my #8 ice cream scoop for large bakery-style cookies or weigh out 4 ounces of cookie dough on my kitchen scale.
  • Bake larger-sized cookies for 11-12 minutes. The edges should set and be slightly golden, and the centers will look a little underdone.
  • Avoid over-baking these cookies; they cook from the residual heat as they cool, resulting in a crisp edge and soft center bakery-style cookie. Yum!
aluminum half sheet pans

Featured Product Aluminum Half Sheet Pans

These are my favorite sheet pans! They will never rust for a lifetime of durability. Perfect for sweet or savory baking; from cookies to sheet pan dinners, this is the pan you’ll reach for.

That is the question. And the answer is… typically no! Chilling monster cookie dough before baking is unnecessary unless it’s humid in your kitchen. 

Butter liquefies in warmer temperatures, so counteracting that is to chill it back to a solid state. Chilled dough will take longer to flatten as the cookie’s structure starts to solidify in the baking process. 

When peanut butter is included as a significant ingredient, cookies usually do not spread like one with butter only. A cookie with peanut butter holds shape compared to a cookie that is all butter-based. Re: having to flatten a peanut butter cookie ball with a fork. 

However, you may benefit from chilling the dough if your peanut butter is thin or runny. Let your dough be your guide. If it feels too sticky or droops when it is scooped, it definitely should go in the fridge until your cookie balls sit nicely on the cookie sheet.

a plate stacked with monster cookies

Storage

Once the cookies cool completely, you can store them in an airtight container on the counter for up to 5 days, or in the refrigerator for up to 2 weeks in a zipper bag or airtight container.

Freeze

Great news! Both baked cookies and cookie dough balls can be frozen successfully in a container or freezer bag. Baked monster cookies can be frozen for up to 3 months, and frozen dough balls up to 6.

Bake From Frozen – on a prepared cookie sheet and add 2-4 minutes to the bake time.

cookies on a counter with M&M's ad chocolate chips with bottle of milk in the background

Recipe FAQs

Why are they called monster cookies?

Monster cookies are named for their large size and the monstrous amount of mix-ins, including M&M’s, chocolate chips, and oats, making them a “monster” of a cookie.

What is the difference between monster cookies and kitchen sink cookies?

A monster cookie is actually a peanut butter oatmeal cookie with M&M’s and chocolate chips added. Kitchen sink cookies are traditionally a vanilla cookie base with a broader range of add-ins, such as different types of nuts, chocolates, dried fruits, pretzels, toffees, and, in some cases, cereal.

How do you keep monster cookies from going flat?

Using fresh baking soda is crucial to prevent monster cookies from going flat. Also, it helps to chill the dough if the brand of peanut butter is runny or your kitchen is humid. Lastly, many baking issues are resolved when the flour is measured correctly.

Can you make this cookie recipe without oats?

Yes, but the monster cookie’s texture will be different when you substitute quick oats in place of rolled oats. Quick oats give the cookies a more cakey texture than rolled oats.

Is it okay to use quick oats instead of rolled oats?

Yes, but the monster cookie’s texture will be different when you substitute quick oats in place of rolled oats. Quick oats give the cookies a more cakey texture than rolled oats.

monster cookies with m&m's on a counter

Substitutions & Additions

Although some people would argue it’s “monstrous” to mess with this particular cookie perfection, there are options galore for switching out monster cookie ingredients. Here are some ideas to add and/or substitute:

  • Coarse Sea Salt Sprinkle or Cinnamon
  • Peanut or Peanut Butter M&M’s
  • Reese’s Pieces
  • Butterscotch chips
  • Rainsin or Craisins
  • White Chocolate or Toffee Nibs
  • Flaked or Toasted Coconut
  • Nuts: Peanuts, Walnuts, or Pecans
peanut butter monster cookies close up

Like This Recipe?

I’d love to hear what you think! Leave a review below and let me know how you liked the recipe!

2 giant bakery style monster cookies with M&M's

Easy Monster Cookies

Yield: 24 cookies
Prep Time: 10 minutes
Bake Time: 8 minutes
Total Time: 18 minutes

Ingredients

  • 1/2 cup salted butter softened
  • 1/2 cup smooth peanut butter
  • 1 cup sugar
  • 1 cup packed light brown sugar
  • 2 large eggs, room temp
  • 2 teaspoons vanilla
  • 1 ¾ cups all-purpose flour
  • 1 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1 cup old-fashioned rolled oats
  • 1 1/4 cups M&M's
  • 1 cup semi-sweet chocolate chips

Instructions

  1. Preheat oven to 350° F. Line two large baking sheets with parchment paper and set aside.
  2. In a large bowl, cream butter, peanut butter, with an electric mixer on high until well combined and creamy. Add sugars and continue mixing on high until light and fluffy (about 1 minute). Add eggs and vanilla and mix until just combined. 
  3. Add flour, baking soda, and salt mixing on low just until incorporated. Scrape the sides and bottom of the bowl and stir briefly. 
  4. Add the oats, M&M's, and chocolate chips and mix by hand until well distributed in the dough.
  5. Scoop the dough into 3 tablespoon balls ( use a 3 Tablespoon cookie scoop - or use a kitchen scale for 2.5 ounce dough balls)  and place onto lined baking sheets with a few inches between them (I usually get 6 on my half-sheet pans).
  6. Bake 8-9 minutes until edges are lightly golden and cookies are puffed. (they don’t spread much). As soon as they come out of the oven you can add a few more M&M's and chocolate chips to the top of the hot cookies. Cool 3-4 minutes on the baking sheet before transferring to a cooling rack to cool completely.

Notes

  • Press extra M&M’s and chocolate chips into the tops right after removing the cookies from the oven.
  • If you would like to make larger cookies, similar to what you’d see in a bakery, scoop out 4 ounces of cookie dough (I like to use my #8 ice cream scoop for this - or weigh out 4 ounces of dough on my kitchen scale) Bake for 11-12 minutes. The edges will be set and slightly golden and the centers will look a little underdone, but they will continue to cook as they cool, resulting in a crisp edge and soft center bakery-style cookie.
  • These cookies are a huge favorite with our family and friends.  My husband especially loves to eat them warm, just a few minutes out of the oven!
  • Once they cool completely, you can store them in an airtight container on the counter for up to 5 days.
Nutrition Information:
Yield: 24 Serving Size: 1
Amount Per Serving: Calories: 268Total Fat: 12gSaturated Fat: 6gTrans Fat: 0gUnsaturated Fat: 5gCholesterol: 27mgSodium: 168mgCarbohydrates: 39gFiber: 2gSugar: 27gProtein: 4g

Nutrition information is estimated based on the ingredients and cooking instructions as described in each recipe and is intended to be used for informational purposes only. Please note that nutrition details may vary based on methods of preparation, origin, and freshness of ingredients used and are just estimates. We encourage, especially if these numbers are important to you, to calculate these on your own for most accurate results.

Did you make this recipe?

Please leave a comment on the blog or share a photo on Instagram

monster cookie poto collage