These extra-large monster cookies are the ultimate cookie! They’re packed with chocolate chips, M&Ms, peanuts, rolled oats, and crispy rice cereal.

These extra-large monster cookies are the ultimate cookie! They're packed with M&Ms, oats, chocolate chips, peanuts, and crispy rice cereal. 

Not surprisingly, chocolate chip cookies are a regular at our house. But sometimes I want to mix things up, go a little crazy with my cookies. Sometimes I just want to open up my pantry and dump all the yummy things I find into the mixer— nuts, candy, the works.

Does this ever happen to you? These monster cookies are the answer. They’ve got everything but the kitchen sink and they are so tasty. While you can add almost anything you want to these cookies (keep reading for variations), I’m a pretty big fan of this combo of chocolate chips, mini M&Ms, peanuts, rolled oats, and crispy rice cereal. They’re thick and chewy, and have a fun flavor and great texture! 

ingredients for monster cookies

What are monster cookies?

Monster cookies are the monster of the cookie world— a combination of a lot of different cookie recipes into one. They taste similar to peanut butter oatmeal cookies with chocolate, but they’re so much more fun that that! You’ll find recipes with varying mix-ins, but here’s what I put in mine:

  • Old-fashioned rolls oats
  • Semisweet chocolate chips
  • Mini M&Ms
  • Chopped peanuts
  • Crispy rice cereal

making monster cookies

Variations and Substitutions

These really are the essential “clean out the pantry” cookies and you are free to change up the mixins to match your craving or what you have on hand already. Here are some ideas:

  • Instead of chocolate chips, use peanut butter chips, butterscotch chips, white chocolate chips, or a combination.
  • Instead of mini M&Ms, use regular M&Ms or Reese’s Pieces.
  • Instead of peanuts, use pecans, walnuts or almonds.
  • Reduce amount of crispy rice cereal and add shredded coconut.

These extra-large monster cookies are the ultimate cookie! They're packed with M&Ms, oats, chocolate chips, peanuts, and crispy rice cereal. 

Cookie Baking Tips

  • Start with butter that has softened to room temperature, but isn’t so warm that it’s at all melted. Your finger should just make a slight indent when pressed, not press all the way through. See my 4 ways to bring butter to room temperature.
  • These pre-cut parchment sheets are perfect for cookie baking. No-mess clean up!
  • If the cookies bake up in an irregular shape, use a flat edge to push the cookie back into a round shape. Do this immediately after removing them from the oven while they’re still soft and malleable.
  • This cookie recipe does not require chilling, they are perfect baked straight from the mixer. But if you want taller, thicker cookies, shape and chill on the sheet pan for 30 minutes before baking. Both ways are great!
  • Store cookies in an airtight container at room temperature for several days.
  • Looking to prep these ahead, or don’t want to bake all the dough right away? See my tips for how to store and freeze cookie dough.

These extra-large monster cookies are the ultimate cookie! They're packed with M&Ms, oats, chocolate chips, peanuts, and crispy rice cereal. 

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5 from 3 reviews

Monster Cookies

Servings: 24 cookies
Prep Time: 15 minutes
Cook Time: 12 minutes
Total Time: 27 minutes
These are the cookies to bake when you aren't sure what you're craving. They're packed with M&Ms, oats, butterscotch chips, pecans, and crispy rice cereal.


  • ¾ cup unsalted butter , at room temperature (85 grams)
  • 1 cup packed light or dark brown sugar (215 grams)
  • ½ cup granulated sugar (100 grams)
  • 2 large eggs
  • 1 tablespoon vanilla extract
  • 2 cups all-purpose flour (240 grams)
  • ½ teaspoons salt
  • 1 teaspoon baking powder
  • ½ teaspoon baking soda
  • 1 ½ cups rolled oats (150 grams)
  • ½ cup mini M&Ms (108 grams)
  • ¾ cup semisweet chocolate chips (128 grams)
  • ½ cup peanuts , chopped (70 grams)
  • 2 ¼ cups crispy rice cereal (70 grams)


  • Preheat oven to 375°F. Line a sheet pan with parchment paper or a silicone baking mat.
  • In the bowl of a stand mixer fitted with a paddle attachment, beat together the butter and sugars until light and creamy, about 1-2 minutes. Add the eggs one at a time, followed by the vanilla and mix until combined.
  • Add the flour, salt, baking powder, and baking soda and mix on low until just combined. Add the oats, chips, and nuts, M&Ms, and crispy rice cereal and mix until just combined.
  • Drop large rounds (I use a #20 - 3 tablespoon cookie scoop) onto the prepared sheet pan, 6-8 per pan. Bake until edges are golden brown and centers are just barely set, about 12 minutes.
  • Let cool on the sheet for 5 minutes, then transfer to a wire rack to cool completely. Store in an airtight container for several days.


Recipe adapted from The Pioneer Woman.
Calories: 244kcal, Carbohydrates: 33g, Protein: 4g, Fat: 11g, Saturated Fat: 6g, Cholesterol: 30mg, Sodium: 85mg, Potassium: 122mg, Fiber: 2g, Sugar: 18g, Vitamin A: 210IU, Calcium: 35mg, Iron: 1mg
Cuisine: American
Course: Dessert
Author: Annalise
Have you tried this recipe?I’d love to hear about it! Leave a review below or take a photo and tag it on Instagram @completelydelicious with #completelydelicious.