These No Flour Monster Cookie Bars are a family favorite and one of the most popular treats on my site! Chewy, sweet, and packed with peanut butter, oats, chocolate chips, and colorful M&M’s, they’re the perfect easy dessert to feed a crowd. And the best part? There’s no flour in the recipe at all!
Whether you’re baking for a party, potluck, or just a weeknight sweet tooth, these cookie bars come together quickly and disappear even faster. Plus, you can easily swap in whatever mix-ins you have in your pantry—peanut butter chips, white chocolate chips, Reese’s pieces, or dark chocolate all work deliciously.
Why You’ll Love These Cookie Bars
- No flour needed – just oats, making them naturally gluten-free (if you use certified gluten-free oats).
- Easy to customize – mix in your favorite candies or chocolate chips.
- Perfect for a crowd – baked in a sheet pan and cut into 40 bars.
- Chewy & soft texture – slightly underbaked so they stay moist and gooey.
Ingredients You’ll Need
- Salted butter
- Brown sugar & granulated sugar
- Creamy peanut butter (not natural)
- Eggs & vanilla extract
- Quick oats + old-fashioned oats
- Baking soda
- Mini M&M’s
- Mini chocolate chips
Tips for the Best No Flour Monster Cookie Bars
- Use regular creamy peanut butter. Natural peanut butter doesn’t have enough oil and can make the bars dry.
- Mix up the oats. A blend of quick oats and old-fashioned oats gives the best chewy texture, but all of one type works too.
- Mini chips & candies work best. They distribute more evenly in bar cookies, but regular-sized will work in a pinch.
- Don’t overbake! They should look slightly underdone in the center when you pull them from the oven. They’ll set up as they cool.
- Want them less sweet? Many readers cut the sugar in half and still love the results.
How to Make No Flour Monster Cookie Bars
- Preheat oven to 350°F. Line a large cookie sheet with parchment paper, a silicone liner, or lightly spray with cooking spray.
- In a large mixing bowl, cream together softened butter, brown sugar, granulated sugar, and peanut butter until light and fluffy.
- Beat in the eggs and vanilla extract until smooth.
- Stir in both oats and baking soda until fully combined.
- Fold in M&M’s and mini chocolate chips, reserving some for the top.
- Spread the dough evenly into the prepared cookie sheet (it helps to drop spoonfuls of dough across the pan and then spread).
- Sprinkle the reserved candies and chips on top and press lightly into the dough.
- Bake for 17–20 minutes, until edges are golden and the center still looks slightly soft.
- Cool completely on the pan for at least 1 hour before slicing into bars.
Storing & Freezing
- Store: Keep bars in an airtight container at room temperature for up to 5 days.
- Freeze: Wrap bars tightly in plastic wrap and store in a freezer-safe bag for up to 2 months. Thaw at room temperature before serving.
More Peanut Butter Dessert Recipes to Try
- Classic Peanut Butter Blossoms
- Peanut Butter Oatmeal Chocolate Chip Cookies
- No-Bake Chocolate Peanut Butter Bars
No Flour Monster Cookie Bars Recipe
Prep Time: 10 minutes
Cook Time: 17 minutes
Total Time: 27 minutes
Servings: 40 bars
Ingredients
- ½ cup (1 stick) salted butter, softened
- 1 cup packed brown sugar
- 1 cup granulated sugar
- 1 ½ cups creamy peanut butter (not natural)
- 3 large eggs
- 1 tablespoon vanilla extract
- 1 ½ cups quick oats
- 3 cups old-fashioned oats
- 1 teaspoon baking soda
- 1 ½ cups mini M&M’s
- 1 cup mini chocolate chips
Instructions
- Preheat oven to 350°F and prepare a large cookie sheet.
- Cream butter, sugars, and peanut butter until fluffy.
- Add eggs and vanilla; mix well.
- Stir in oats and baking soda.
- Fold in M&M’s and chocolate chips.
- Spread dough evenly in prepared pan.
- Top with extra candies and bake 17–20 minutes.
- Cool completely before cutting into bars.