Flourless Peanut Butter-Chocolate Chip Oat Bars | browneyedbaker.com

I have a long-standing love affair with all recipes that combine peanut butter, chocolate chips and oats. I can’t resist making them and I can’t ever stop eating them, either!

I’ve seen so many flourless cookie recipes floating around the web for years now, and they’ve always piqued my interest, but I had never tried any of them. I assumed they would be wonderfully dense, soft and a little bit gooey, which really sounds like the best kind of cookie! When I saw a flourless bar recipe fashioned after monster cookies, including my beloved peanut butter, chocolate chips and oats, I was all over it.

Flourless Peanut Butter-Chocolate Chip Oat Bars | browneyedbaker.com

Nearly all bar recipes are made in a square 8-inch or 9-inch pan or a standard 9×13 pan, but not these! They go all out and are made in a half sheet pan, no messing around here. It’s absolutely perfect if you need them for a party or work function (if you don’t have a pan large enough, I’ve included a note below the recipe for scaling!).

While the original recipe called for topping these with regular M&M’s (which is pretty standard for monster cookies), I have to be honest. Regular ol’ M&M’s don’t really do much for me… give me peanut, peanut butter or pretzel M&M’s and I’m totally on board, but since we were already rocking the chocolate and peanut butter combo in these bars, I thought it was fitting to top them with (drum roll) Reese’s Pieces.

A good decision, indeed.

Flourless Peanut Butter-Chocolate Chip Oat Bars | browneyedbaker.com

One year ago: Strawberry Shortcake
Two years ago: Blueberry Buckle
Four years ago: Malted Milk Ice Cream
Five years ago: Cranberry Orange Scones

Flourless Peanut Butter-Chocolate Chip Oat Bars

An entire half sheet pan full of peanut butter-oat bars loaded with chocolate chips and topped with Reese's Pieces.
5 (2 ratings)


  • cup (151.33 g) salted butter, at room temperature
  • 2 cups (440 g) light brown sugar
  • 1⅓ cups (266.67 g) granulated sugar
  • 4 eggs
  • 1 teaspoon vanilla extract
  • teaspoons (1.5 teaspoons) baking soda
  • 2 cups (516 g) crunchy peanut butter, creamy peanut butter is fine, too
  • 6 cups (486 g) old-fashioned oats, NOT quick-cooking oats
  • 1 cup (180 g) semisweet chocolate chips
  • ½ cup (94 g) Reese's Pieces


  • Preheat oven to 350 degrees F. Lightly grease a 13x18-inch half sheet pan.
  • With an electric mixer, beat the butter and both sugars together on medium speed until light and fluffy, about 3 minutes. Scrape down the sides of the bowl and add the eggs, one at a time, beating well after each addition. Add the vanilla extract and baking soda and beat to combine.
  • Using a rubber spatula, stir in the peanut butter until completely combined, then stir in the oats, then the chocolate chips until all of the ingredients are fully mixed together.
  • Turn the dough out onto the prepared baking sheet and, using your hands, press into an even layer (the dough may be slightly sticky, in which case you can dampen your hands to keep it from sticking). Sprinkle the Reese's Pieces on top and gently press into the dough.
  • Bake until the bars are just lightly browned and no longer look wet on top, 15 to 17 minutes. Remove from the oven and allow to cool completely before cutting into bars. These can be stored in an airtight container, at room temperature, for up to 1 week.


Note: If you do not have a 13x18-inch pan and want to use a 9x13, cut all of the ingredients in half. You may need to start checking for doneness a few minutes early.
Nutritional values are based on one serving
Calories: 289kcal, Carbohydrates: 35g, Protein: 6g, Fat: 14g, Saturated Fat: 5g, Cholesterol: 27mg, Sodium: 158mg, Potassium: 203mg, Fiber: 2g, Sugar: 23g, Vitamin A: 135IU, Calcium: 32mg, Iron: 1.4mg

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