Gluten-Free Monster Cookie Bars

These gluten-free monster cookie bars are loaded with peanut butter, oats, chocolate chips, and M&Ms. Easy flour-based recipe perfect for busy families!

You know those afternoons when your kids burst through the door asking for “something sweet” and you realize you haven’t been to the store in days? That’s exactly when I created my first batch of gluten-free monster cookie bars.

I had a jar of peanut butter, some oats, and a bag of M&Ms leftover from a birthday party, and honestly? These bars saved the day.

What I love most about this recipe is how forgiving it is. Whether you’re brand new to gluten-free baking or you’ve been doing this for years, these dessert bars gluten free come together in one bowl with ingredients you probably already have.

No fancy techniques, no complicated steps—just simple, crowd-pleasing magic that happens to be gluten-free.

According to the Celiac Disease Foundation, more families are embracing gluten-free baking as they navigate celiac disease and gluten sensitivity. But here’s the thing: gluten-free doesn’t mean taste-free. These bars prove it every single time.

Gluten-Free Monster Cookie Bars Recipe Card

Prep Time: 15 minutes
Cook Time: 25 minutes
Total Time: 40 minutes (plus cooling)
Servings: 24 bars

Ingredients

• ¾ cup butter or dairy-free butter, softened (1½ sticks)
• 1 cup brown sugar, packed
• ⅓ cup cane sugar
• 2 teaspoons vanilla extract
• 2 large eggs
• ¾ cup peanut butter or nut/seed butter of choice (I used Natural Creamy Peanut Butter—not the bottom of the jar if possible)
• 1½ cups gluten-free all-purpose flour with xanthan gum* (We used GF Jules flour)
• 1½ teaspoons baking soda
• 1 teaspoon baking powder
• ½ teaspoon salt
• 1½ cups gluten-free oats
• ¾ cup semi-sweet chocolate chips or chips of choice
• ¾ cup M&Ms or chocolate candy of choice (we love Unreal Milk Chocolate Gems too!) plus ½ cup more for topping

Instructions

1. Preheat oven to 350°F and line a 9×13 baking pan with parchment paper, or grease the pan. Set aside.
2. Using a stand mixer or hand mixer, mix butter, sugars, and vanilla until well combined and creamy.
3. Add eggs and beat thoroughly.
4. Beat in peanut butter until smooth and fully incorporated.
5. In a separate small bowl, add flour, baking soda, baking powder, and salt. Mix with a fork or pastry cutter. Then add the flour mixture to the creamed mixture and mix until combined.

1. Add in oats and mix till combined.
2. Add in chocolate chips and M&Ms and gently mix till combined.
3. Spoon batter into the prepared baking pan and spread evenly. Top with additional M&Ms, pressing gently into the batter.
4. Bake for 25 minutes, or until golden and a toothpick comes out clean. You do not want to over-bake.
5. Let cool in the pan for 45 minutes or longer. Lift the entire parchment paper out and transfer to a cutting board. Cut into 24 squares.
6. Store in an airtight container at room temperature for 5 days. These freeze beautifully too!

Why These Gluten-Free Monster Cookie Bars Work Every Time

I’ve made these easy nut free desserts (when using sunflower seed butter) at least two dozen times, and they’ve never let me down. The secret? The combination of peanut butter and oats creates this wonderfully chewy texture that makes you forget you’re eating anything gluten-free.

The flour based recipes I use most often need that perfect balance of structure and tenderness. This one nails it because the gluten-free all-purpose flour provides stability while the oats add heartiness and the peanut butter keeps everything moist and rich.

Smart Substitutions for Every Kitchen

Butter: Any dairy-free butter works beautifully here. I’ve used Earth Balance and Miyoko’s with great results. Coconut oil also works in a pinch, though it changes the flavor slightly.

Peanut Butter: For nut-free households, sunflower seed butter or WowButter are excellent swaps. These easy nut free desserts become allergy-friendly without sacrificing taste. Just make sure you’re using a no-stir variety for the best texture.

Gluten-Free Flour: I prefer blends with xanthan gum already included (like GF Jules or King Arthur Measure for Measure). If your flour doesn’t have it, add ¾ teaspoon xanthan gum to the dry ingredients.

Oats: Certified gluten-free oats are essential here. Bob’s Red Mill and GF Harvest are my go-to brands. Quick oats work too if that’s what you have.

Chocolate: Use whatever makes your heart happy! Dark chocolate chips, white chocolate, or even chopped-up candy bars all work. For dairy-free dessert bars gluten free, reach for Enjoy Life chips.

Troubleshooting Your Monster Cookie Bars

Too Crumbly? This usually means the bars were overbaked or the peanut butter was too dry. Natural peanut butters can vary in moisture content, so if yours seems super thick, add a tablespoon of milk to the batter.

Too Gooey in the Middle? Give them more time! Every oven runs differently, and gluten-free flour based recipes sometimes need an extra 3-5 minutes. The edges should be golden and pulling slightly away from the pan.

Spreading Too Much? Make sure your butter is softened but not melted. Room temperature is key for these dessert bars gluten free. If your kitchen is warm, pop the mixed batter in the fridge for 15 minutes before baking.

Falling Apart When Cut? Patience, friend! I know it’s hard, but letting these gluten-free monster cookie bars cool completely makes all the difference. The structure sets as they cool, and rushing it leads to crumbly messes.

Storage and Make-Ahead Magic

These bars are actually better the next day (if they last that long). The flavors meld together overnight, and the texture becomes even chewier.

Room Temperature: Keep them in an airtight container for up to 5 days. I like to slip parchment paper between layers to prevent sticking.

Freezer: These freeze like a dream! Wrap individual bars in plastic wrap, then store them all in a freezer-safe container for up to 3 months. Thaw at room temperature or warm them slightly in the microwave for that fresh-baked feel.

Meal Prep Tip: I double this recipe every few weeks and freeze half. Then I have easy nut free desserts ready for lunch boxes, after-school snacks, or those “I need chocolate NOW” emergencies.

Serving Ideas That’ll Make You the Hero

Warm these gluten-free monster cookie bars slightly and serve with a scoop of vanilla ice cream. The contrast of warm, chewy cookie and cold, creamy ice cream is perfection.

Pack them in lunch boxes with a note that says “You’re loved.” Trust me, your kids will remember those little moments.

Crumble a bar over yogurt for breakfast. Yes, I said breakfast. Life’s too short not to have chocolate for breakfast sometimes.

Stack them on a plate for parties. According to research on gluten-free diets, bringing safe desserts to gatherings helps those with celiac disease feel included without drawing unnecessary attention.

Pair them with your favorite gluten-free banana bread for a weekend brunch spread that’ll impress everyone.

Fun Variations to Try

Triple Chocolate: Swap the peanut butter for almond butter and use all chocolate chips—no M&Ms. Add ¼ cup cocoa powder to the dry ingredients for flour based recipes that are deeply chocolatey.

Kid-Friendly Version: Let your little ones choose the mix-ins! We’ve done Reese’s Pieces, crushed pretzels, and even dried cranberries. These dessert bars gluten free are forgiving enough to handle whatever you throw at them.

Dairy-Free: Use dairy-free butter and chocolate chips. The result? Easy nut free desserts that are also dairy-free and just as delicious.

Healthier Swap: Replace half the chocolate with dried fruit or coconut flakes. You’ll still get that sweet satisfaction with a bit more nutrition.

Birthday Cake Version: Add ½ cup rainbow sprinkles to the batter and use white chocolate chips. These gluten-free monster cookie bars become instant party favorites.

Gluten-Free Monster Cookie Bars FAQs

Why These Gluten-Free Monster Cookie Bars Belong in Your Recipe Box

I’m not exaggerating when I say this is one of the most-requested recipes at our house. Between soccer practices and homework battles, having a batch of these in the freezer feels like a secret superpower.

They work for birthday parties, bake sales, and regular Tuesday afternoons. They travel well, freeze perfectly, and make everyone happy—whether they’re gluten-free or not. And honestly? That’s what matters most.

These flour based recipes don’t require special equipment or hard-to-find ingredients. You probably have most of what you need right now. So grab that peanut butter, preheat your oven, and let’s make some magic happen.