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Marshmallow Peanut Butter Fluffernutter Bars

These Marshmallow Peanut Butter Fluffernutter Bars are soft, gooey, and full of that nostalgic peanut butter and marshmallow flavor, perfect for sharing and comforting treats.
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Prep Time 15 minutes
Cook Time 30 minutes
Total Time 1 hour 15 minutes
Servings: 16 bars
Course: Dessert
Cuisine: American
Calories: 160
Ingredients Method Notes

Ingredients
  

For the peanut butter dough
  • 0.5 cup salted butter, softened
  • 0.5 cup creamy peanut butter (Jif or Skippy style, not natural) For best results, use a smooth, shelf-stable peanut butter.
  • 0.75 cup packed brown sugar You can swap light brown sugar for a milder flavor.
  • 0.25 cup granulated sugar
  • 1 large egg
  • 1 teaspoon vanilla extract
  • 1 cup all-purpose flour Can be replaced with gluten-free baking flour in a 1:1 ratio.
  • 0.5 teaspoon baking soda
  • 0.25 teaspoon baking powder
  • 0.25 teaspoon salt Add a pinch more if using unsalted butter.
For the marshmallow layer
  • 1 cup marshmallow fluff (creme, not regular marshmallows) Spreads and melts easier than regular marshmallows.

Method
 

Preparation
  1. Preheat the oven to 350°F (175°C) and prepare a 9x9-inch pan by lining it with parchment paper, leaving some overhang.
  2. In a large bowl, beat together the softened butter, creamy peanut butter, brown sugar, and granulated sugar with a hand mixer for about 30 seconds.
  3. Add the egg and vanilla extract to the mixture, and beat on high until light and fluffy.
Mixing the Dough
  1. In a separate bowl, whisk together the flour, baking soda, baking powder, and salt.
  2. Add the dry ingredients to the wet mixture and stir on low speed until just combined, being careful not to overmix.
Building the Bars
  1. Press about two-thirds of the dough evenly into the bottom of the prepared pan.
  2. Spread the marshmallow fluff over the dough. If it’s sticky, lightly grease your spatula before spreading.
  3. Dollop the remaining dough over the marshmallow layer in small pieces, gently spreading it without worrying if some marshmallow shows through.
Baking
  1. Bake the bars in the preheated oven for 25 to 30 minutes or until the edges are lightly golden and the center is puffed.
Cooling and Serving
  1. Let the bars cool slightly in the pan before lifting them out using the parchment paper.
  2. Cool for about 30 minutes more, then slice into 16 bars.

Notes

Store the bars in an airtight container at room temperature for up to 4 days, or refrigerate for up to 1 week. For freezing, wrap tightly and freeze for up to 2 months. Rewarm in the microwave if you like them warm, but don't overheat.