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.

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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.

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.

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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.

When you are baking, 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.

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!

To Chill Or Not To Chill Monster Cookie Dough?

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.

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