Oat Flour Monster Cookies
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These gluten-free oat flour monster cookies are thick, soft, chewy, and loaded with creamy peanut butter, melty chocolate chips, and colorful candy. They have everything you love about a classic monster cookie but made completely with oat flour (no gluten-free flour needed!).
A spin on our favorite oat flour chocolate chip cookies, these are the kind of fun, crowd-pleasing cookie that disappears from the cooling rack fast. Whether you are baking for a birthday, a lunchbox treat, or simply a very good cookie moment at home, these come together in one bowl with real ingredients and no complicated steps.
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real deal approved
A nostalgic monster cookie...that's gluten-free!
Oat flour is one of my favorite budget-friendly ways to bake gluten-free because you can easily make your own by blending old-fashioned rolled oats into a fine flour.
It creates cookies with soft, tender centers while letting all the classic monster cookie flavors shine. The brown sugar, peanut butter, and melted butter give them that rich, chewy texture, while the oats add just enough heartiness to make every bite feel like a true monster cookie.
Don't skip the 30-minute chill! This gives the oat flour time to fully absorb moisture, which helps prevent the cookies from spreading too much in the oven. The result is thicker, chewier cookies with soft, bakery-style centers.
Why you will love these oat flour monster cookies
- Soft and chewy: Oat flour and a quick chill give these cookies tender centers with lightly golden edges.
- One-bowl easy: Melt the butter, whisk the wet ingredients, stir in the dry ingredients, and fold in the fun stuff. No electric mixer needed!
- Loaded with mix-ins: Chocolate chips and M&M's make every bite colorful, chocolatey, and kid-approved.
- Easy to make gluten-free: Use certified gluten-free oats and oat flour for a cookie everyone at the table can enjoy with confidence.
Ingredient notes
- Oat flour: I recommend a fine, certified gluten-free oat flour for the most consistent texture. You can also blend certified gluten-free old-fashioned oats into a fine flour, then measure after blending.
- Old-fashioned oats: These add the signature hearty monster-cookie chew. If you are baking for celiac disease or a serious gluten sensitivity, make sure they are certified gluten-free.
- Creamy peanut butter: Use a smooth, well-stirred peanut butter. A conventional creamy peanut butter gives the most dependable result here.
- Butter: Unsalted butter keeps the flavor rich and classic. For a dairy-free batch, use a melted dairy-free butter that you already know bakes well.
- Chocolate chips and M&M's: Semi-sweet chocolate balances the sweet, peanut-buttery dough beautifully. Press a few extra pieces over the scoops before baking for that irresistible bakery look. If you keep kosher, make sure the m&m's are labeled kosher, as some seasonal ones may not be.
How to make oat flour monster cookies
These cookies are incredibly simple to make. The key is to let the dough chill before baking, then pull the cookies while the centers still look a touch soft.
Mix the wet ingredients
In a large mixing bowl, whisk the melted butter, brown sugar, granulated sugar, and creamy peanut butter until smooth. Add the eggs and vanilla, then whisk again until fully combined.
Finish the dough
Stir in the oat flour, old-fashioned oats, baking soda, kosher salt, and cinnamon until no dry streaks remain. Fold in the chocolate chips and M&M's.
Chill and scoop
Cover and chill the dough for 30 minutes. Heat the oven to 350°F and line two baking sheets with parchment. Scoop 3 tablespoons of dough, about 50 to 55 grams each, onto the sheets, leaving 2 inches between each cookie. Press extra chocolate chips and M&M's onto the tops.
Bake and cool
Bake for 11 minutes, rotating the pans as needed, until the edges are lightly golden and the centers still look slightly underbaked. Let the cookies cool on the baking sheets for 10 minutes before transferring them to a wire rack. They finish setting as they cool and stay wonderfully chewy in the center.
Pro tips
My best tips for chewy cookies
- Do not skip the chill: Oat flour needs a little time to absorb moisture. Chilling prevents excess spread and gives you a thicker cookie.
- Use the first batch as your guide: If the cookies spread more than you like, increase the oat flour to 2½ cups, or 240 grams, next time.
- Adjust only if needed: If your cookies bake up thicker than you prefer, reduce the oat flour to 2 cups, or 192 grams, or add 1 tablespoon of milk to the dough.
- Underbake slightly: Take the cookies out when the centers still look soft. They continue setting on the hot pan, which is how you get that soft, chewy center.
- Finish with flaky salt: A tiny pinch right after baking makes the chocolate and peanut butter flavors pop.
Storage and freezing
- Storage: Keep cooled cookies in an airtight container at room temperature for up to 4 days. I love these because of how long they stay soft!
- Freezing baked cookies: Freeze fully cooled cookies in an airtight container or freezer bag for up to 2 months. Let them thaw at room temperature or warm one briefly in the microwave.
- Freezing dough: Scoop the chilled dough onto a parchment-lined sheet and freeze until firm. Transfer the dough balls to a freezer bag, then bake from frozen, adding 1 to 2 minutes as needed.
More oat flour recipes to try
Gluten-Free Oat Flour Monster Cookies
Ingredients
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Instructions
- In a food processor, blend 2.5 cups old-fashioned oats until a fine flour. Set aside.
- In a large mixing bowl, whisk the ½ cup unsalted butter, melted, 1 cup light brown sugar, ¼ cup granulated Sugar, and ½ cup creamy peanut butter until smooth. Add 2 large eggs and 1 tablespoon vanilla extract, then whisk until fully combined.
- Stir in the previously blended oat flour, 1 cups old-fashioned oats (whole), 1 teaspoon baking soda, 1 teaspoon kosher salt, and ¼ teaspoon cinnamon (optional) until no dry streaks remain. Fold in 1 cup semi-sweet chocolate chips or chunks and 1 cup M&M's.
- Cover the dough and refrigerate for 30 minutes. This gives the oat flour time to hydrate and helps the cookies hold their shape.
- Heat the oven to 350°F. Line two baking sheets with parchment paper.
- Scoop 3 tablespoons of dough, about 50 to 55 grams each, onto the prepared baking sheets, spacing them 3 inches apart. Press a few extra M&M's and chocolate chips into the tops.
- Bake for 12-14 minutes, until the edges are lightly golden and the centers still look slightly underbaked. The centers will look raw but will firm up significantly once they cool.
- Cool the cookies on the baking sheets for 10 minutes, then transfer to a wire rack to cool completely. Sprinkle with flaky sea salt, if desired.
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