Fluffernutter Bars with Peanut Butter and Marshmallow

There is something downright magical about Fluffernutter Bars with Peanut Butter and Marshmallow that instantly takes you back to childhood snack times, but in a grown-up, dessert-form that’s utterly irresistible. These bars combine the rich, nutty creaminess of smooth peanut butter with a gooey, glorious marshmallow middle layer, all wrapped in a soft and chewy texture that’s perfectly sweet and salty. If you adore the classic Fluffernutter sandwich or just love the playful duo of peanut butter and marshmallow, this recipe is by far one of the most delicious treats you’ll want to bake again and again.

this Recipe

Ingredients You’ll Need

Don’t let the ingredient list intimidate you—each component is straightforward, familiar, and works together beautifully to give you that perfect balance of flavors and textures. From the tender flour base to the luscious peanut butter and fluffy marshmallow, everything here is essential to create your next favorite bar.

• All-purpose flour (2 1/4 cups): The foundation that gives the bars their soft, chewy texture without overpowering the flavor.
• Baking powder (1 teaspoon): Helps the bars rise just enough for a tender crumb.
• Salt (1/4 teaspoon): A pinch to enhance the sweetness and balance the richness.
• Unsalted butter, softened (3/4 cup): Adds creaminess and richness for that melt-in-your-mouth bite.
• Brown sugar (3/4 cup): Adds moisture and caramel-like depth to the sweetness.
• White sugar (1/3 cup): Brings light sweetness and helps with the proper texture.
• Smooth peanut butter (1 1/2 cups): The star ingredient, providing that luscious peanut flavor and creamy consistency.
• Large egg (1) and egg yolk (1): Bind everything together sturdily while keeping the bars tender.
• Marshmallow fluff (7 oz jar): The gooey, dreamy middle layer that makes these Fluffernutter Bars with Peanut Butter and Marshmallow truly unforgettable.

How to Make Fluffernutter Bars with Peanut Butter and Marshmallow

Step 1: Prepare Your Oven and Pan

Kick things off by preheating your oven to 350 degrees Fahrenheit, and get your oven rack positioned in the middle to ensure even baking. Line a 9×13 inch pan with parchment paper or foil, leaving some overhang so it’s easier to lift out the bars later. Taking this small prep step now sets you up for success and easy cleanup.

Step 2: Mix the Dry Ingredients

In a medium bowl, whisk together the flour, baking powder, and salt. This dry combo forms the backbone of your bars, giving them structure without making them heavy or dense.

Step 3: Cream the Butter and Sugars, Then Add Peanut Butter

Using a mixer, beat the softened butter with both brown and white sugars until the mixture feels soft and creamy. Then, mix in the smooth peanut butter, which will give the bars their trademark rich and nutty flavor. This step is crucial for achieving the perfect balance of moisture and richness.

Step 4: Add Eggs and Incorporate Flour Mixture

Beat in the large egg and extra egg yolk until everything looks smooth and well combined. With your mixer on low, slowly add the flour mixture about half at a time, blending gently to keep the dough tender.

Step 5: Reserve Some Dough and Form Base Layer

Take about 1 cup of the peanut butter dough out and set it aside—that will become the topping later. Press the remaining dough evenly into the bottom of your prepared pan, forming a sturdy but soft base for those fluffy marshmallow layers.

Step 6: Bake the Peanut Butter Base

Bake the base layer for about 25 minutes or until the top looks fully set. This is the perfect moment to get that deep golden color and that wonderful baked peanut butter flavor which will marry beautifully with the sweet marshmallow.

Step 7: Add Marshmallow Fluff Layer

Once that base layer is done baking, carefully spread the entire jar of marshmallow fluff over the warm peanut butter layer. The heat from the base helps the fluff spread smoothly, creating that luscious gooey middle you’ll love.

Step 8: Add Topping and Finish Baking

Pinch off the reserved peanut butter dough into small, flattened pieces about 1 inch in size, and place them gently over the marshmallow, covering about 80 to 90 percent. Pop the pan back into the oven for another 10 minutes, letting the top layer set and slightly brown but stay soft and inviting.

Step 9: Cool and Slice

After baking, allow the bars to cool at room temperature for at least an hour—this step helps the marshmallow layer firm up a bit and makes slicing easier. Use the parchment overhang to lift the bars out, and with a lightly greased thin knife, slice into 15 squares to reveal those dreamy layers.

How to Serve Fluffernutter Bars with Peanut Butter and Marshmallow

Garnishes

These bars are fantastic just on their own, but you can elevate them by lightly dusting with powdered sugar or adding a drizzle of melted chocolate for a touch of decadence. A sprinkle of crushed peanuts also gives a lovely crunch contrast and amps up the peanut butter vibe.

Side Dishes

Serve your Fluffernutter Bars with a chilled glass of milk or a hot cup of coffee to complement their richness. For a fancier touch, pair them with a scoop of vanilla ice cream or a fresh fruit salad to cut the sweetness and add freshness to your dessert spread.

Creative Ways to Present

Try cutting these bars into fun shapes using cookie cutters for parties or gift-giving, or layer them in clear jars for a colorful, portable treat. Wrapping individual bars in parchment paper tied with a cute ribbon makes for irresistibly charming gifts.

Make Ahead and Storage

Storing Leftovers

Once cooled, keep your Fluffernutter Bars with Peanut Butter and Marshmallow in an airtight container at room temperature. They stay perfectly soft and fresh for up to five days, making them a great make-ahead dessert or snack.

Freezing

If you want to stash some for later, wrap the bars individually or as a whole block tightly in plastic wrap and place in a freezer-safe container. They freeze well for up to two months—just thaw overnight in the fridge before enjoying.

Reheating

Warm bars gently in the microwave for 10 to 15 seconds if you prefer them soft and melty, especially the marshmallow layer. Avoid overheating to keep the bars from drying out or the marshmallow from becoming too sticky.

FAQs

Can I use crunchy peanut butter instead of smooth in these bars?

You absolutely can! Just increase the amount slightly to about 1 3/4 cups since crunchy peanut butter tends to be less dense. This will add a wonderful texture contrast with some nutty crunch.

Is natural peanut butter suitable for this recipe?

I don’t recommend natural or homemade peanut butter here because it can separate and change the oil content, which affects the texture and consistency of the bars. Stick to a stable, smooth peanut butter for best results.

What pan works best when baking Fluffernutter Bars with Peanut Butter and Marshmallow?

A metal 9×13 pan helps create crispier edges, while a glass pan will yield slightly softer edges. Both work fine, but choose based on your edge preference.

Can I make these bars gluten-free?

With a simple substitution of gluten-free all-purpose flour blend for regular flour, you can make these bars gluten-free. Just ensure your baking powder is gluten-free as well.

Why is it helpful to grease the knife before slicing?

Greasing your knife lightly with cooking spray helps prevent the gooey marshmallow layer from sticking, resulting in neater slices and less frustration.

Final Thoughts

I can’t recommend making these Fluffernutter Bars with Peanut Butter and Marshmallow enough—each bite feels like a nostalgic hug wrapped in sweet, peanut buttery goodness with a dreamy marshmallow twist. Whether for a casual snack, a family dessert, or a special occasion treat, these bars hit all the right notes and will quickly become a beloved favorite. So grab your ingredients, preheat that oven, and get ready to share a little slice of delicious fun!

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