Fluffernutter Peanut Butter Bars

These Fluffernutter Bars bring together the perfect combination of peanut butter richness and sweet marshmallow fluff for a dessert that feels nostalgic and indulgent. They are a fun twist on the classic sandwich, baked into a bar that is easy to share and hard to resist.

I first made these bars for a family gathering, and they vanished so quickly I had to double the recipe next time around. They have since become a favorite treat whenever a sweet craving hits.

Ingredients

• All purpose flour: the base that gives structure to the bars, make sure it is fresh for the best texture
• Baking soda: helps the bars rise slightly and gives a tender crumb
• Salt: balances the sweetness and enhances flavor, use fine salt for even mixing
• Unsalted butter: adds richness and moisture, room temperature is key for proper creaming
• Smooth peanut butter: the key flavor component, smooth variety ensures a creamy filling and dough
• Granulated sugar: sweetens and helps with texture, use regular table sugar
• Light brown sugar: adds moisture and depth with its molasses notes, pack lightly in the measuring cup
• Large eggs: bind everything together and add richness, use room temperature for smooth mixing
• Vanilla extract: enhances all the other flavors with its warm aroma
• Marshmallow fluff: the signature topping that adds sweetness and a billowy texture, use a good quality jarred type
• Powdered sugar: for the filling’s sweetness and smoothness, sifted to avoid lumps
• Heavy cream: adds creaminess and helps adjust the filling to the perfect spreadable consistency

Step-by-Step Instructions

Spoon Preheat and Prepare Your Pan:

Preheat your oven to 350 degrees Fahrenheit. Grease and line a 9x9 inch baking pan with parchment paper, leaving extra overhang on the sides so you can lift the bars out easily once baked.

Sift and Mix Dry Ingredients:

In a medium bowl, whisk together the all purpose flour, baking soda, and salt. This helps distribute leavening evenly for a consistent texture.

Cream Butters and Sugars:

In a large bowl, use a mixer to cream the butter, peanut butter, granulated sugar, and brown sugar together on medium speed until the mixture turns light in color and fluffy in texture, about two to three minutes. This is important to incorporate air for lighter bars.

Add Eggs and Vanilla:

Beat in the eggs one at a time, making sure each one is fully incorporated before adding the next. Stir in the vanilla extract until the mixture is smooth and evenly combined.

Combine Wet and Dry Ingredients:

Gradually add the flour mixture to the wet ingredients, mixing on low speed just until no streaks of flour remain. Avoid overmixing to keep the bars tender.

Press Dough into Pan and Bake:

Transfer the dough to your prepared pan and press it evenly to cover the entire surface. Bake for 25 to 30 minutes until the edges are lightly golden and a toothpick inserted in the center comes out clean. Let the bars cool slightly while you make the filling.

Whip Up the Peanut Butter Filling:

In a medium bowl, beat together the peanut butter and butter until smooth. Add the sifted powdered sugar, vanilla extract, and two tablespoons of heavy cream. Beat until creamy and smooth. If needed, add the remaining tablespoon of cream to reach a spreadable consistency.

Spread Filling Over Warm Bars:

Use a spoon or an offset spatula to evenly spread the peanut butter filling over the slightly warm bars. This helps the filling set nicely.

Warm and Spread Marshmallow Fluff:

Heat the marshmallow fluff in the microwave for about 10 seconds to soften it. Spread it evenly over the peanut butter layer for that iconic sweet and fluffy topping.

Cool Completely and Slice:

Allow the bars to cool fully in the pan before using the parchment overhang to lift them out and cut into squares. These are best served at room temperature for the perfect combination of creamy and chewy.

My favorite part is the peanut butter filling which balances perfectly with the sweet marshmallow fluff. Making these bars always reminds me of childhood snacks but with an adult upgrade that everyone loves.

Storage Tips

Store these bars in a sealed container at room temperature for up to five days to keep them soft and fresh. For longer storage, wrap them tightly and freeze for up to three months. Thaw at room temperature before slicing and serving.

Ingredient Substitutions

If you prefer natural peanut butter choose one with no added oils for a cleaner flavor but the texture may be less smooth.
You can swap heavy cream in the filling with whole milk but it will be slightly less rich and thick.
For a gluten free version try a 1 to 1 gluten free flour blend but watch the texture as it may vary slightly.

Serving Suggestions

These bars are perfect on their own with a glass of cold milk or served alongside a scoop of vanilla ice cream for an over-the-top dessert experience. A sprinkle of chopped peanuts on top adds great crunch and visual appeal.

Cultural Context

The Fluffernutter sandwich has been a beloved American treat since at least the early 20th century, combining peanut butter and marshmallow fluff between slices of bread. These bars capture that nostalgia while turning it into a handheld dessert that’s easy to share and celebrate.

Frequently Asked Questions

What type of peanut butter is best to use?

Using smooth peanut butter ensures a creamy texture that blends well into both the base and filling, providing even flavor and moisture.

How do I know when the bars are fully baked?

They should be lightly browned on top, and a toothpick inserted into the center should come out clean or with just a few moist crumbs.

Can the marshmallow fluff be warmed before spreading?

Yes, warming the marshmallow fluff slightly in the microwave softens it, making it easier to spread evenly over the filling.

Is it important to let the bars cool before adding the topping?

Letting the bars cool slightly prevents the filling and fluff from melting, helping maintain distinct layers and texture.

How should these bars be stored?

Store in an airtight container at room temperature for up to three days or refrigerate for longer freshness, ensuring the layers stay intact.