Print
clock clock iconcutlery cutlery iconflag flag iconfolder folder iconinstagram instagram iconpinterest pinterest iconfacebook facebook iconprint print iconsquares squares iconheart heart iconheart solid heart solid icon
Close-up of layered dessert bars with a crumbly crust, a creamy filling, and a crunchy nut topping.

Classic Fluffernutter Blondie Bars with Marshmallow Frosting


  • Author: Samantha Brooks
  • Total Time: 45 minutes
  • Yield: 24 Bars 1x
  • Diet: Vegetarian

Description

The ultimate nostalgic treat, bringing together creamy peanut butter and sweet marshmallow fluff. Featuring a dense, chewy peanut butter blondie base and a cloud-like marshmallow frosting, these bars offer a perfect harmony of salty and sweet, finished with crunchy roasted peanuts.


Ingredients

Scale

The Peanut Butter Base

  • 3/4 cup unsalted butter, melted
  • 3/4 cup creamy peanut butter
  • 1 1/2 cups all-purpose flour
  • 1 cup brown sugar & 1/2 cup granulated sugar
  • 2 large eggs, 2 tsp vanilla, 1/2 tsp salt

The Marshmallow Frosting

  • 1 (7-oz) container marshmallow fluff
  • 2 cups powdered sugar
  • 1/2 cup unsalted butter, softened
  • Topping: 1/2 cup chopped roasted peanuts

Instructions

Prep: Preheat oven to 350°F. Grease a 9×13-inch pan.

Mix: Beat melted butter with sugars. Add eggs, vanilla, and peanut butter; mix until smooth. Gently stir in flour and salt.

Bake: Spread into pan. Bake for 25–30 mins until golden. Cool completely.

Frosting: Beat softened butter and fluff until smooth. Gradually add powdered sugar until light and fluffy.

Assemble: Spread frosting over cooled bars and sprinkle with chopped peanuts. Chill before slicing.

Notes

The ‘Meltdown’ Warning: Marshmallow fluff is temperature-sensitive; the base must be cold to the touch to prevent the frosting from turning into a glaze.

Softened vs. Melted: Use room temperature butter for the frosting to hold the air bubbles needed for stability.

Texture Control: Stop mixing the blondie base as soon as flour streaks disappear to keep the bars fudgy rather than bread-like.

  • Prep Time: 15 minutes
  • Cook Time: 30 minutes
  • Category: Dessert / Snack
  • Method: Beating / Baking
  • Cuisine: American Nostalgia

Nutrition

  • Serving Size: 1 Bar
  • Calories: 280
  • Sugar: 26
  • Sodium: 145
  • Fat: 16
  • Saturated Fat: 8
  • Unsaturated Fat: 8
  • Trans Fat: 0.3
  • Carbohydrates: 32
  • Fiber: 1
  • Protein: 4
  • Cholesterol: 40

Keywords: fluffernutter bars, peanut butter marshmallow bars, marshmallow fluff frosting, peanut butter blondies, sweet and salty desserts, easy bake sale recipes, childhood nostalgia treats