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Monster Cookies are BIG chewy cookies loaded with peanut butter, oats, M&Ms, and chocolate chips. A classic cookie recipe that the whole family will love!

detail image of a monster cookie cooling on a wire rack

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Everyone enjoys M&M cookies, peanut butter cookies, oatmeal cookies, and chocolate chip cookies. So what happens when you put them all together? Well, you get these monster cookies! They’re mega-big, super chewy, and everything delicious all rolled together into one tasty cookie.

If you’ve never had monster cookies before, trust me: you’re going to love them. And if you have had them before, you’re going to want to grab this recipe so you can make them at home whenever the craving strikes!

top down close up image of a monster cookie

Flavor-wise, these monster cookies are quite unique. They have M&Ms and chocolate chips in them, but they don’t taste like M&M or chocolate chip cookies because of the peanut butter. But they’re not really like peanut butter cookies either, since they have oats folded into the dough for added texture.

In other words, monster cookies are unlike any other cookie recipe you’ve tried before!

Although M&Ms and chocolate chips are standard for monster cookies, you can definitely switch things up to make the recipe your own. Amp up the peanut butter flavor by using Reese’s Pieces and peanut butter chips, use milk chocolate chips instead of bittersweet for a milder flavor, or add chopped peanuts to the mix for some crunch.

ingredients to make monster cookies

Ingredients

See recipe card below this post for ingredient quantities and full instructions.

  • Unsalted butter – This needs to be softened; set it on the counter for about 30 minutes before starting the recipe.
  • Light brown sugar
  • Creamy peanut butter – Don’t use natural peanut butter here! You want the regular peanut butter that doesn’t need to be stirred before using.
  • Egg – Here’s the best way to crack an egg.
  • Vanilla extract
  • Baking soda
  • All-purpose flour
  • Kosher salt
  • Quick oats – You can substitute old-fashioned oats (AKA rolled oats) for more oat-y texture.
  • M&Ms – You can use the mini M&Ms if you’d like, but I prefer the regular-size milk chocolate M&Ms.
  • Bittersweet chocolate chips – Semi-sweet chocolate chips are fine too!

Make them peanut-free:

You can substitute sunflower seed butter for the peanut butter and make these monster cookies nut-free!

steps to make monster cookies

How to Make Monster Cookies

1. Prepare

Preheat your oven to 350ºF and line a baking sheet with parchment paper or a silicone baking mat (Silpat). 

2. Mix the Wet Ingredients

In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, sugar, and peanut butter until the mixture is fluffy, which should take about 3 to 4 minutes. Add the egg and vanilla and continue to mix, scraping down the sides of the bowl as needed. 

Tip: If you don’t have a stand mixer, you can use a hand mixer with regular beaters instead. 

3. Finish the Cookie Dough

In another mixing bowl, whisk together the baking soda, flour, and salt. Set the mixer speed to low and slowly add the dry ingredients to the wet ingredients and mix until just combined. Fold in the oats, M&Ms, and chocolate chips.

4. Bake the Cookies

Spoon 2 tablespoon portions of dough onto the prepared baking sheet (or use a large cookie scoop), with 2 inches of space between them. Bake for 11 to 13 minutes or until the edges are golden brown, then gently press down on the top of each cookie with the back of a spoon to flatten. Cool on the baking sheet for 10 minutes, then transfer the cookies to a wire rack to finish cooling. 

Tip: You can set aside a few M&Ms and chocolate chips, then gently press them into the tops of the cookies after they’re done baking. This is optional, but it’s the secret to making your cookies look like they came from a bakery—it lets you make sure each cookie has the perfect amount of M&M candies and chocolate chips on top!

Tip:

You can set aside a few M&Ms and chocolate chips, then gently press them into the tops of the cookies after they’re done baking. This is optional, but it’s the secret to making your cookies look like they came from a bakery—it lets you make sure each cookie has the perfect amount of M&M candies and chocolate chips on top!

close up image of monster cookies served on parchment paper

How to Store Monster Cookies

These cookies can be stored in an airtight container at room temperature for 4 to 5 days, although they’re best eaten within a day or two.

You can also freeze the cookie dough for up to 3 months, so consider making a double batch and freezing half of it for future use! When you’re ready to bake, just add a few extra minutes to the oven time to account for the dough being frozen.

stack of four monster cookies served on a plate

FAQs

Are monster cookies gluten-free?

No, monster cookies are not gluten-free. However, you could try making them with gluten-free oats and a gluten-free all-purpose flour blend (use a measure-for-measure substitute, not a single flour like almond flour or coconut flour).

Can monster cookies be frozen?

Once monster cookies are baked, you can freeze them in a freezer-safe container for up to 3 months. Thaw frozen cookies at room temperature or in the microwave. (They also make a great base for ice cream sandwiches!)

Why are my monster cookies flat?

There are a few reasons why your monster cookies might be flat. First, the butter may have been too soft. Let it soften for 30 minutes, but no more than this. Another reason could be that your flour measurement was inaccurate and you used too little. Finally, if you have to use the same baking sheet twice for two batches of cookies, make sure you let the sheet cool down first. Putting dough on a hot sheet will cause the cookies to spread and flatten. (Learn more here: How to Make Cookies.)

Monster Cookies

Monster Cookies are BIG chewy cookies loaded with peanut butter, oats, M&Ms, and chocolate chips. A classic cookie recipe that everyone will love!
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Course: Dessert
Cuisine: American
Author: Kasey Schwartz
Servings: 28 cookies
Prep Time: 12 minutes
Cook Time: 13 minutes
Total Time: 25 minutes

Ingredients  

  • ½ cup unsalted butter softened
  • 1 cup light brown sugar packed
  • ¾ cup creamy peanut butter
  • 1 large egg room temperature
  • 2 tsp vanilla extract
  • 1 tsp baking soda
  • 1 ¼ cups all-purpose flour
  • ½ tsp kosher salt
  • ½ cup quick oats
  • ¾ cup M&Ms
  • ½ cup bittersweet chocolate chips

Instructions 

  • Preheat the oven to 350F. Line a baking sheet with parchment or a silicon mat.
  • In the bowl of an electric mixer fitted with a paddle, cream together the butter, sugar, and peanut butter until fluffy, about 3-4 minutes. Add the egg and vanilla and continue to mix, scraping the sides as needed.
  • In a separate bowl, combine the baking soda, flour, and salt and stir to mix. With the speed on low, slowly add the dry ingredients to the bowl and mix until just combined. Do not overmix. Add the oats, M&Ms, and chocolate chips and mix until just combined.
  • Spoon 2 tablespoon portions of dough onto the prepared baking sheet, leaving 2-inches in between each one. Bake for 11-13 minutes or until the edges are golden brown. Gently press down on the top of each cookie with the back of a spoon to flatten. Allow to cool on the baking sheet for 10 minutes. Transfer the cookies to a wire rack to finish cooling.

Nutrition

Calories: 174kcal | Carbohydrates: 20g | Protein: 3g | Fat: 9g | Saturated Fat: 5g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 3g | Trans Fat: 0.1g | Cholesterol: 15mg | Sodium: 123mg | Potassium: 84mg | Fiber: 1g | Sugar: 13g | Vitamin A: 123IU | Vitamin C: 0.05mg | Calcium: 30mg | Iron: 1mg
Keyword: cookies, cookies, m&m cookies, holiday baking, monster cookies
Did you make this recipe?Mention @kasey_allthingsmamma or tag #allthingsmamma!

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About Kasey Schwartz

Hi, I’m Kasey, Founder of All Things Mamma – where I am dishing up family favorite recipes that are easy to make with simple, everyday ingredients. Plus – tips and tricks for living your best life!

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