These Fluffernutter Brownies are pure indulgence. Imagine a rich, fudgy brownie base that’s swirled with gooey marshmallow fluff and creamy peanut butter in every bite. It’s that sweet spot where childhood nostalgia and serious chocolate cravings meet. Perfect for bake sales, casual gatherings, or just a decadent night in, these brownies offer everything you love about the classic fluffernutter sandwich—but baked into dessert form.

The crispy top gives way to a deeply chocolatey center, and then there’s the surprise layer of melted peanut butter and pockets of sticky marshmallow that make each square wildly satisfying. They’re easy to make with a few pantry staples and look like they came straight from a bakery window. Whether you’re a marshmallow fan, a peanut butter lover, or a brownie aficionado, this recipe hits all the right notes.

What Kind of Peanut Butter Should I Use?

Creamy peanut butter works best for that signature smooth swirl, but chunky can add an extra texture twist if that’s your thing. Avoid natural peanut butters with oil separation, as they don’t bake as consistently and can throw off the structure of the brownie. Classic store-bought creamy PB delivers that rich, sweet-salty balance we want in a Fluffernutter.

Ingredients for the Fluffernutter Brownies

Unsalted Butter – Adds richness and creates that chewy texture in the brownies.

Granulated Sugar – Sweetens the batter and helps create a crackly top.

Brown Sugar – Adds depth of flavor and moisture to keep the brownies fudgy.

Eggs – Provide structure and richness. Let them come to room temp for better mixing.

Vanilla Extract – A touch of vanilla balances the deep chocolate flavor.

All-Purpose Flour – Just enough to give the brownies structure without making them cakey.

Unsweetened Cocoa Powder – Choose a high-quality cocoa for maximum flavor.

Salt – Essential for balance, especially with all the sweetness.

Marshmallow Fluff – The star of the show for that gooey, stretchy sweetness.

Peanut Butter – Adds salty richness and classic fluffernutter vibes.

Chocolate Chips or Chunks (optional) – If you want even more chocolate pockets inside.

How To Make the Fluffernutter Brownies

Step 1: Prep the Pan and Preheat

Preheat your oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper, leaving a bit of overhang for easy removal.

Step 2: Melt the Butter

In a medium saucepan or microwave-safe bowl, melt the unsalted butter until smooth and warm. Let it cool slightly.

Step 3: Mix the Sugars and Eggs

Whisk in the granulated sugar and brown sugar until fully combined. Add in the eggs and vanilla extract, whisking until the mixture becomes glossy and slightly thickened.

Step 4: Add the Dry Ingredients

Stir in the unsweetened cocoa powder, all-purpose flour, and salt. Mix until just combined—don’t overmix to keep the brownies fudgy.

Step 5: Swirl in the Good Stuff

Pour half the batter into the prepared pan. Drop spoonfuls of marshmallow fluff and peanut butter across the surface. Use a knife or skewer to gently swirl them together. Top with the remaining batter and add a few more dollops of fluff and peanut butter on top if desired.

Step 6: Bake to Perfection

Bake for 28–32 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Let cool completely in the pan before slicing.

How to Serve and Store Fluffernutter Brownies

These brownies are best served slightly warm or at room temperature so the peanut butter and fluff remain soft and gooey. Pair them with a cold glass of milk or top with a scoop of vanilla ice cream for an extra treat.

To store, place them in an airtight container at room temperature for up to 3 days. For longer storage, refrigerate for up to a week or freeze for up to 2 months. Just be sure to wrap them individually before freezing to maintain that rich texture.

Frequently Asked Questions

How do I get clean cuts with gooey brownies?

Let the brownies cool completely before slicing, and use a sharp knife wiped clean between each cut.

Can I use marshmallows instead of fluff?

You can, but marshmallow fluff melts into the batter better and gives a more consistent gooey swirl.

Should I use natural or conventional peanut butter?

Stick to conventional peanut butter. Natural varieties can be oily and affect the texture.

Can I double the recipe for a larger pan?

Yes! Double everything for a 9×13-inch pan and bake a little longer, checking for doneness around 35 minutes.

Are these freezer-friendly?

Absolutely. Let them cool, cut them, then wrap each square tightly before freezing for up to 2 months.

Can I add extra toppings?

Yes—try crushed peanuts, a drizzle of chocolate, or even chopped Reese’s for more texture and flavor.

Want More Brownie Ideas with a Twist?

If you love these Fluffernutter Brownies, you’ll probably enjoy these other favorites:

• Caramel Cheesecake Cookies for a rich, creamy bite in cookie form.
• Condensed Milk Snow Cookies for a soft, melt-in-your-mouth texture.
• Lemon Raspberry Swirl Cheesecake Cups for a fruity-tart twist.
• Brown Butter Dulce de Leche Rice Krispie Treats for something chewy, buttery, and sweet.
• Chocolate Instant Pudding if you need a quick chocolate fix.

📌 Save this recipe to your Pinterest dessert board so you can come back to it any time.

And let me know in the comments how yours turned out. Did you layer in extra fluff? Try it with Nutella instead of peanut butter?

I love hearing how others make these recipes their own. Questions are welcome too—let’s help each other bake smarter.

Looking for more gooey dessert ideas? Follow along on Pinterest at Life with Jam for daily sweet inspiration.