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Reeses Peanut Butter Smores Oatmeal Cookie Bars

These Reeses Peanut Butter Smores Oatmeal Cookie Bars are a decadent, chewy treat loaded with peanut butter, chocolate, and marshmallow fluff!
Prep Time20 minutes
Cook Time30 minutes
Total Time50 minutes
Course: Dessert
Cuisine: American
Keyword: Cookie Bars, Easy, Oatmeal, Peanut Butter, S'mores
Servings: 12 servings

Ingredients

  • 12 tablespoons melted butter
  • 2 cups light brown sugar
  • 1 cup creamy peanut butter
  • 2 eggs room temperature
  • 1 tablespoon vanilla extract
  • 1.5 cups all-purpose flour
  • 0.75 cup graham cracker crumbs
  • 1 cup old-fashioned oats
  • 1 tablespoon cornstarch
  • 2 teaspoons baking powder
  • 0.5 teaspoon salt
  • 1 cup Reese's peanut butter baking chips
  • 7 bars full-size Hershey's chocolate bars
  • 7 ounces marshmallow fluff
  • 1 cup Reese's miniatures chopped

Instructions

  • Preheat your oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, leaving some overhang on the sides for easy removal later.
  • In a large mixing bowl, whisk together the melted butter and light brown sugar until combined. Add in the creamy peanut butter, eggs, and vanilla extract. Mix until everything is smooth and well incorporated.
  • In another bowl, combine the all-purpose flour, graham cracker crumbs, old-fashioned oats, cornstarch, baking powder, and salt. Stir the dry ingredients together to ensure even distribution.
  • Gradually add the dry ingredient mixture to the wet ingredients. Use a rubber spatula to fold everything together until just combined. Be careful not to overmix.
  • Fold in the Reese's peanut butter baking chips and chopped Reese's miniatures into the dough until evenly distributed.
  • Spread half of the cookie dough evenly into the prepared baking pan, pressing down gently to form an even layer.
  • Place the full-size Hershey's chocolate bars over the cookie dough layer, ensuring they are evenly spaced. Then, spread the marshmallow fluff over the chocolate layer, creating a gooey and delicious topping.
  • Using the remaining cookie dough, drop spoonfuls over the marshmallow fluff. It’s okay if it doesn’t completely cover the marshmallow; it will spread while baking.
  • Bake in the preheated oven for 25-30 minutes, or until the edges are golden brown and the center is set. You want a slightly gooey texture in the center.
  • Allow the bars to cool in the pan for at least 15 minutes. Use the parchment paper to lift them out of the pan and transfer to a cutting board. Slice into squares and enjoy!

Equipment

  • 9x13 inch baking pan
  • Mixing Bowls
  • Whisk
  • Rubber spatula
  • Parchment Paper

Notes

  • Line your baking pan with parchment paper for easy removal and no sticking.
  • For a gluten-free version, substitute the all-purpose flour with a gluten-free blend.
  • Don’t overbake; bars should be set but still slightly gooey in the center.
  • Store bars in an airtight container at room temperature for up to 5 days or refrigerate for up to a week.
  • Freeze wrapped bars for up to 3 months for longer storage.