The Best Monster Cookies (Secretly Gluten-Free)

Baked Monster Cookies layered together on a dark wood background

I’ve gone through my share of Monster Cookie recipes. I had an old stand-by that I used for years until, to my astonishment, I topped it with this one. These Monster Cookies rely on the power of oats liquid-absorbing ability. The downside is that this recipe requires the dough to sit in the refrigerator for 4 hours to allow the oats to absorb the peanut butter-laden mixture. If you are in a pinch and need cookies like 5 minutes ago, I highly encourage you to check out my Oatmeal Raisins Cookies with Whole Wheat Flour. If you are still on board for getting your perfect Monster Cookie fix, let’s dive in.

First off, these cookies happen to be gluten-free. I saw the perfect opportunity to accomplish this when I realized I only needed a minuscule amount of flour and I can amplify the oat flavor. Of course, who doesn’t want more oats in their monster cookies? Secondly, I admit these aren’t authentic Monster Cookies. Or at least not the way I make them. I make them using 100% chocolate candies. I am a messy eater, and the candy coating prevents the chocolate from melting all over my hands, shirt, and jeans. Yes, I get it everywhere. If you are a Monster Cookie die-hard and want the chocolate chips and chocolate candy mixture, feel free to do a 50:50 mixture. I’ll be over here with my clean shirt.

ingredients for recipe in different size bowls
dry mixture and wet mixture in separate bowls
peanut butter added to mixed wet mixture
colored candies on top of cookie dough
cookie dough in arranged in 3 straight lines on a baking sheet

These Monster Cookies are overflowing with oats and peanut butter and have a healthy dose of chocolate. They are thick and chewy with a wholesome mouthfeel that makes them appropriate for any time of day. The sugar is an afterthought, only there to highlight the main ingredients and make them sing. Don’t be surprised if you can’t eat just one; you aren’t the only one.

cookies cooling on a baking sheet
monster cookies with a broken cookie in the middle

Possible Substitutions for these monster cookies

OAT FLOUR. If gluten isn’t an issue, feel free to substitute oat flour for whole wheat flour, all-purpose flour or 50% all-purpose flour, and 50% whole wheat flour

Monster Cookies for the holidays

red, white, and blue colored M&M cookies

I typically use naturally color-coated chocolate candies in these cookies. There is always one person who asks me how I get the M&M’s to change colors. I smile and let them in on my secret. For holiday parties, I often use M&M’s since they change colors for each holiday season. This makes these cookies infinitely adaptable for any holiday throughout the year.

Before you start: Baking Tips

As much as I love the peanut flavor of old-fashioned peanut butter, commercial peanut butter is best here due to the high amount of oil separation in old-fashioned peanut butter. I use Jif Natural peanut butter as a happy compromise since it contains minimal ingredients (peanuts, sugar, palm oil with 2% or less salt and molasses). Otherwise, use whichever commercial peanut butter you like to eat.

More Sweet Recipes to Try


The Best Monster Cookies (Secretly Gluten-Free)

Truly the best monster cookies! They are thick and chewy and bursting with oats and peanut butter with a healthy dose of chocolate. You will never guess they are gluten-free.

  • Author: Kim
  • Prep Time: 15 minutes
  • Refrigerate Time: 4 hours
  • Cook Time: 33 minutes
  • Total Time: 4 hours, 48 minutes
  • Yield: 24 cookies 1x
  • Category: Dessert
  • Method: Bake
  • Cuisine: American
  • Diet: Gluten Free


  • 2 1/4 cups (225g) old-fashioned oats
  • 1/4 cup (24g) oat flour*
  • 1 1/8 teaspoons baking soda
  • 1/4 teaspoon salt
  • 5 Tablespoons (70g) unsalted butter, melted
  • 1/2 cup (100g) light brown sugar
  • 1/2 cup (100g) white granulated sugar
  • 2 large eggs
  • 1 cup plus 2.5 tablespoons (170g) creamy commercial-style peanut butter
  • 1/2 cup (4oz) chocolate candies, dark or milk chocolate*


  1. Combine the dry ingredients. In a large bowl, stir the oats, flour, baking soda, and salt together until combined.  
  2. Make the cookie dough. In the bowl of a stand mixer with a paddle attachment or a large bowl with a hand mixer, combine the melted butter, brown and white sugars, and beat on medium speed until smooth, about 2 minutes. Beat in the eggs, 1 at a time, until completely incorporated, about 2 minutes. Make sure there are no visible egg streaks in the batter. Add the peanut butter and mix until fully combined, about 3 minutes. Reduce the speed to low, and add 1/3 of the flour mixture at a time to the wet ingredients. Mix on low speed after each flour addition until combined. Stir in the chocolate candies. 
  3. Refrigerate. Cover the bowl tightly with plastic wrap and refrigerate for at least 4 hours. After 4 hours, you can bake all of the cookies or freeze some for later. See notes for freezing instructions.
  4. Bake. Adjust an oven rack to the middle of the oven. Preheat oven to 350°F (180°C). Line three half-sheet baking sheets with parchment paper. Scoop the cold dough in 2-tablespoon (45g) balls and arrange them 2-inches apart on the baking sheets. No need to roll the balls after scooping! Bake one baking sheet at a time until the edges are light golden brown, about 11-12 minutes.  Remove the baking sheet from the oven and transfer the baking sheet to a wire rack and let the cookies cool completely on the baking sheet. 


OAT FLOUR. If you opt to measure by volume instead of weight, whisk the flour first to aerate it, then spoon into a measuring cup, and then level it off with the back of a knife. If using whole wheat flour or all-purpose flour, only use 6 tablespoons (48g). 

CHOCOLATE CANDIES. If you choose to substitute some or all of the chocolate candies for chocolate chips, measure by weight instead of volume for the best results.

STORAGE. Store in an airtight container for 3 days at room temperature.

DO AHEAD. This cookie dough freezes wonderfully. Scoop the dough into 2-tablespoon balls, place them 1/2-inch apart on a sheet pan, and put the sheet pan in the freezer until the dough balls are frozen (about 2 hours). Once the dough balls are frozen, store them in a bag in the freezer until ready to bake. Bake them directly from the freezer and add 1-2 minutes to the total baking time. 


  • Serving Size: 1 cookie
  • Calories: 153 calories
  • Sugar: 11.1g
  • Sodium: 143mg
  • Fat: 8.0g
  • Saturated Fat: 3.2g
  • Carbohydrates: 17.8g
  • Fiber: 1.4g
  • Protein: 1.7g
  • Cholesterol: 22mg

Keywords: monster cookies, gluten-free monster cookies, chewy monster cookies

Did you make this recipe?

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