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Close up of an Oatmeal Monster Cookie topped with M&Ms and Chocolate chips

The Best Monster Cookies

5 Stars 4 Stars 3 Stars 2 Stars 1 Star 4 from 2 reviews
  • Author: Julianne Dell
  • Prep Time: 10 minutes
  • Cook Time: 13 minutes
  • Total Time: 23 minutes
  • Yield: 12-14 Cookies
  • Category: Dessert
  • Method: Baked
  • Cuisine: American


Homemade Monster Cookies are loaded with creamy peanut butter, rich chocolate, and crunchy M&Ms. These easy cookies are the perfect combination of sweet and salty!


  • ½ cup (113g) butter, at room temperature
  • ½ cup (264g) creamy peanut butter
  • ½ cup (95g) granulated sugar
  • ½ cup (110g) light brown sugar, packed
  • 1 large egg
  • 2 teaspoons (10ml) pure vanilla extract
  • ¾ cups (105g) all-purpose flour
  • ¾ cups (72g) rolled oats
  • ½ teaspoon baking soda
  • ¼ teaspoon salt
  • ½ cup (90g) semi-sweet chocolate chips
  • ½ cup (90g) M&Ms


  1. Preheat the oven to 350° F. Combine the softened butter with peanut butter and beat until completely smooth; scrape down the bowl occasionally. Next add the brown and granulated sugar. Beat on medium speed until well combined, 2-3 minutes.
  2. Next add the eggs and vanilla extract and continue beating until well incorporated.
  3. In a separate bowl, combine the remaining dry ingredients, except the chocolate chips and M&Ms. Stir to combine and slowly add the dry ingredients into the dough, mixing on low speed until dough starts to form. Before the dough thickens, add the chocolate chips and M&Ms. Beat a couple of times just until the flour incorporates.
  4. Line a baking sheet with parchment paper or a silicone baking sheet. Scoop the dough using a large cookie scoop and place on a sheet pan, 2 inches apart. Place additional M&Ms and chocolate chips on top of the cookies if desired.
  5. Bake for 11-13 minutes. The center of the cookie should be slightly under baked but not too gooey. Allow to cool on the baking sheet for 5-10 minutes before transferring to a wire rack to cool. Store in an airtight container.


  • Peanut butter: Be sure to use creamy peanut butter like Jif or Skippy, and not natural peanut butter. 
  • Store finished cookies in an airtight container
  • Freeze cookie dough: Scoop the dough into balls and place them in a freezer-safe container. Thaw to room temperature and bake according to the instructions. 
  • Freeze finished cookies: To freeze baked cookies, just allow the cookies to cool completely. Once cooled, place them in a freezer-safe container. 
  • Double the recipe for a large batch


  • Serving Size: 1 cookie
  • Calories: 309
  • Sugar: 26g
  • Sodium: 149mg
  • Fat: 16g
  • Carbohydrates: 37g
  • Fiber: 1.9g
  • Protein: 4.9g
  • Cholesterol: 34mg