Thick, chewy monster cookies studded with oats, chocolate chips, and a generous scoop of Reese’s pieces for extra peanut butter flavor. Make these for the peanut butter lover in your life!

Monster cookies with Reese's pieces on a cooling rack.

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In the market for a simple, delicious treat you can bake in no time? Look no further! These ultimate Reese’s monster cookies are easy to make and completely addictive. Consider yourself warned.

What is a monster cookie?

A classic monster cookie is made up of peanut butter and oats, with generous quantities of chocolate chips and M&Ms mixed into the batter.

They are beloved by many, but due to the large amount of oats — and the unusually small amount of flour — they can be surprisingly tricky, and some recipes for them are downright unreliable. Too flat, too puffy, too hard, too crumbly… you get the picture.

Fortunately, you can cut to the chase. I’ve experimented quite a bit since first embarking on my monster cookie journey with a recipe from Baked, and this is the version I’ve settled on for life.

White tray with monster cookies.

Why you’ll love them

  • Peanut butter + chocolate = love. Period, end of story.
  • Chewy, soft texture. Adding a bit more flour to the dough allows you to enjoy all the oat and peanut butter flavor without tolerating a dry, crumbly cookie.
  • No dough chilling. Enough said!
  • Normal size batch. Very often monster cookie recipes are written for a truly humongous batch of cookies — like 4 or 5 dozen. While there’s certainly a place for that, that’s a lot of ingredients, and most of us don’t that many cookies lying around most of the time.

Of course, you don’t need to use Reese’s pieces in these cookies specifically. You can do everything else exactly the same, mix in M&Ms, and have a more traditional monster cookie. Using Reese’s is simply my favorite way to double up the peanut butter love, and it makes them festive for fall, as well.

How to make monster cookies with Reese’s

This is about as easy as it gets. The dough comes together in one bowl, and as noted above, there’s no chilling required.

The one pro tip to keep in mind: mix quickly and thoroughly at first, then slow down as you add more ingredients. This keeps the texture and consistency perfect!

  1. Cream together butter and sugar, then mix in wet ingredients. Blend really well at this stage.
  2. Sprinkle on dry ingredients, and mix on low speed just until combined.
  3. Add mix-ins and stir by hand.
  4. Scoop and bake. Voila! Cookies!
Monster cookies on a cooling rack.

Storage and freezing tips

Storage. Cookies keep well tightly covered at room temperature for 3-4 days.

Make Ahead. The dough for these monster cookies can be made in advance and chilled in the refrigerator for up to 3 days. Allow it to sit at room temperature for 30-60 minutes, then scoop and bake as directed.

Freezing. You can also freeze the unbaked balls of cookie dough for up to 3 months, and bake straight from frozen. Monster cookies on demand!

To do this, simply make the dough as directed, scoop mounds onto a parchment-lined baking sheet or plate, and place in the freezer, uncovered, for about an hour. (This will flash-freeze the dough balls so they don’t stick together and are easy to separate when you want to bake them later.) After an hour, combine the frozen cookie dough balls in an airtight container or zip-top plastic bag. When ready to bake, place cookies directly from the freezer onto a parchment-lined baking sheet, and bake as directed, adding just 2-3 minutes to the baking time.

Reese's monster cookies arranged on a white tray, with glasses of milk nearby.

More easy cookie recipes

If you try these Reese’s monster cookies, don’t forget to rate the recipe and leave a comment below. I love hearing how recipes turn out in your kitchen, and it helps other readers, too.

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Monster cookies with Reese's pieces on a cooling rack.
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Ultimate Reese’s Monster Cookies

Thick, chewy cookies with soft centers, studded with oats, chocolate chips, and a generous scoop of Reese's pieces for extra peanut butter flavor. Make these for the peanut butter lover in your life!

Ingredients

  • 1/2 cup butter at room temperature
  • 1/2 cup granulated sugar
  • 1/2 cup packed brown sugar light or dark
  • 1/2 cup creamy peanut butter
  • 1 large egg
  • 1 teaspoon vanilla extract
  • 1 and 1/4 cups old-fashioned rolled oats
  • 1 cup all-purpose flour
  • 1/2 teaspoon baking soda
  • 1/4 teaspoon salt
  • 1 cup Reese’s Pieces or other peanut butter-filled candies
  • 1/2 cup semi-sweet chocolate chips

Instructions

  • Preheat oven to 350 degrees F. Line cookie sheets with parchment paper or silicone mats, if desired, and set aside.
  • Using an electric mixer if possible, cream together butter, granulated sugar, and brown sugar until the mixture is very light and fluffy. Add peanut butter, egg, and vanilla and mix again until evenly combined.
  • Sprinkle oats, flour, baking soda, and salt over the mixture and mix on low speed, just until incorporated. Try not to over mix at this point!
  • Add Reese’s Pieces and chocolate chips and stir gently by hand. Scoop dough out into roughly 1-inch balls and place on cookie sheets.
  • Bake for 10-12 minutes, just until the tops are golden and barely set. They will continue to harden as they cool. Cool for about 15 minutes on the pans, then remove to wire racks to cool completely.

Notes

  • Oat Substitution: You can substitute quick oats for the rolled oats in a pinch; the texture will be slightly different.
  • Storage: Cookies keep well in an airtight container for 3-4 days.
  • Freezing: These cookies are very well suited to freezing as dough balls! Prepare dough and shape into 1-inch balls as directed, then place them with space in between them on a parchment-lined baking sheet or plate. Transfer to the freezer for about 1 hour. This flash freezes the cookies so they don’t stick together. You can then layer them in a freezer bag or container and freeze up to 3 months. Bake straight from frozen, adding 2-3 minutes to the baking time.

Nutrition Estimate

Calories: 198kcal, Carbohydrates: 23g, Protein: 4g, Fat: 10g, Saturated Fat: 5g, Cholesterol: 17mg, Sodium: 125mg, Potassium: 114mg, Fiber: 1g, Sugar: 15g, Vitamin A: 128IU, Calcium: 19mg, Iron: 1mg
Did you make this recipe?Leave a review below, then snap a quick picture and tag @nourishandfete on Instagram so I can see it!

This post was originally published October 29, 2016, and has been updated with new photos, more relevant text, and improvements to the recipe yield and ingredient ratios.