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A whole tray of monster cookies sitting with an orange napkin.
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5 from 11 votes

Peanut Butter Monster Cookies

Course Sweets & Dessert
Cuisine American
Prep Time 10 minutes
Cook Time 12 minutes
Total Time 22 minutes
Servings 18 cookies
Calories 215kcal
Author Kristine Underwood

Ingredients

  • 1/2 cup unsalted butter (room temperature)
  • 1/2 cup sugar
  • 1/4 cup brown sugar (light or dark, packed)
  • 1/2 cup peanut butter (creamy, not natural peanut butter)
  • 1 egg
  • 1 tsp vanilla extract
  • 3/4 cup rolled oats (not quick-cooking oats *see notes)
  • 3/4 cup flour (all-purpose, spooned and leveled)
  • 1/2 tsp baking soda
  • 1/2 tsp sea salt
  • 1/2 cup M&M candies (mini)
  • 1/2 cup chocolate chips (mini or full-size *see notes)

Instructions

  • Preheat oven to 350 degrees Fahrenheit and line 3 baking sheets with parchment paper. Set aside.
  • In a large bowl (or the bowl of your stand mixer) cream butter, sugar, and brown sugar on medium speed for 1-2 minutes until light and fluffy.
  • Add the peanut butter, egg, milk, and vanilla extract to the bowl and mix for an additional minute, but avoid adding too much air to the dough.
  • Add the rolled oats, flour, baking soda, and sea salt to the bowl and mix just until crumbly, but not completely mixed.
  • Using a wooden spoon or a spatula, fold in the M&Ms and chocolate chips and mix until incorporated, but try to avoid over-mixing.
  • Using a 3 TBS cookie scoop, scoop dough onto lined cookie sheets at least 2 inches apart.
  • Bake for 12 minutes, rotating the pans halfway through baking.
  • Let the cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
  • Store cookies in an airtight container at room temperature for 3-4 days or freeze for up to 3 months.
Notes
  • Use rolled oats over quick-cooking oats. Rolled oats hold their shape better during baking, giving the cookies structure and chew without turning to mush. Quick oats will make the cookies thinner and less substantial, but if that's all you have, it's better than nothing.
  • Measure the ingredients carefully, particularly the four. Too much flour can make the dough dry and the cookies thick and cakey.
  • Overdoing the mix-ins (especially candies) can cause the cookies to puff up, but super thick, and spread unevenly.
  • Use smaller (mini) mix-ins for the best texture. Oversized candies or chocolate chips can weigh down the dough and result in thicker, chunkier cookies that don't spread like they should.
  • This dough is wet and sticky, so don’t panic. This definitely isn’t a dough you want to handle (so I always use scoop).
  • Don’t overmix the cookie dough. Once you add the dry ingredients, mix just until combined. Overworking the dough can make the cookies tough.
  • Take the cookies out when the centers are puffed up, but still look soft. They’ll finish setting up on the baking sheet as they cool. Underbaking helps keep the centers nice and chewy.
  • Swap chocolate chips for butterscotch chips, or add a handful of finely chopped pretzels for a salty crunch. You could even ramp up the peanut butter and substitute half the chocolate chip for peanut butter chips.
Nutrition
Serving: 1 cookie | Calories: 215kcal | Carbohydrates: 23g | Protein: 4g | Fat: 13g | Saturated Fat: 6g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 4g | Trans Fat: 0.2g | Cholesterol: 24mg | Sodium: 136mg | Potassium: 96mg | Fiber: 1g | Sugar: 15g | Vitamin A: 186IU | Vitamin C: 0.03mg | Calcium: 21mg | Iron: 1mg