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A plate of monster cookies which are made with oats, peanut butter, chocolate chips and M&M's.

Monster Cookies

These monster cookies are soft and chewy peanut butter oatmeal cookies loaded with chocolate chips and M&M's. An easy and classic cookie that's perfect for parties, after school snacks and special occasions.
Course Dessert, Snack
Cuisine American
Prep Time 10 minutes
Cook Time 15 minutes
Total Time 25 minutes
Servings 24 servings
Calories 159kcal
Author Sara Welch


  • 1/2 cup butter softened
  • 3/4 cup brown sugar
  • 1/4 cup granulated sugar
  • 1 egg
  • 1/2 cup peanut butter I prefer creamy but crunchy will also work
  • 1 teaspoon vanilla extract
  • 1 cup all purpose flour
  • 1/2 teaspoon baking soda
  • 1 1/4 cups rolled oats
  • 1 cup M&M's plus more for tops of cookies
  • 1/2 cup semisweet chocolate chips plus more for tops of cookies


  • Preheat the oven to 350°F.
  • Line a sheet pan with a piece of parchment paper or silicon baking mat.
  • Place the butter, brown sugar, and granulated sugar in the bowl of a mixer. Beat until light and fluffy, 1-2 minutes.
  • Add the egg, peanut butter and vanilla to the bowl and mix until combined.
  • Add the flour and baking soda to the bowl and mix until just combined. Stir in the oats.
  • Add the M&M's and chocolate chips to the bowl and gently fold them into the dough.
  • Make 2 tablespoon sized balls of cookie dough and place them 2 inches apart on the prepared sheet pan. You will need to bake the cookies in batches.
  • Press a few M&M's and chocolate chips onto the top of each cookie dough ball.
  • Bake for 11-13 minutes or until edges are lightly browned. 
  • Cool the cookies on the pan for 5 minutes, then transfer to a cooling rack.
  • Repeat the process with the remaining cookie dough. Cool all cookies completely then serve.
  • Store any leftover cookies in a sealed container for up to 5 days, or you can freeze the cookies for up to 2 months.



Adapted from Live Well Bake Often.


Calories: 159kcal | Carbohydrates: 18g | Protein: 2g | Fat: 8g | Saturated Fat: 3g | Cholesterol: 17mg | Sodium: 86mg | Potassium: 88mg | Fiber: 1g | Sugar: 10g | Vitamin A: 130IU | Calcium: 15mg | Iron: 0.8mg