Fluffernutter Brownies

By Lily | Last modified on Mar 4, 2026

Featured in: Desserts

Fluffernutter Brownies are a delightful twist on traditional brownies, combining the rich, fudgy texture of chocolate with the creamy indulgence of peanut butter and fluffy marshmallow. These layered treats are perfect for those who crave a balance between intense cocoa flavor and sweet, nutty comfort.

Baking these brownies creates a luscious sandwich of smooth peanut butter and airy marshmallow fluff nestled between dense, chocolatey layers. It’s the perfect dessert to impress friends or satisfy your own sweet tooth with a nostalgic flavor profile.

Why You’ll Love This Recipe

Unique combination of creamy peanut butter and marshmallow fluff enhances classic fudge brownies with extra flavor layers.
The luscious textures from gooey marshmallow and fudgy brownie create a perfectly indulgent bite every time.
Uses common baking ingredients with a simple layering technique for minimal fuss and maximum wow factor.

Ingredients

Regular unsweetened cocoa powder (1 ⅓ cups / 167.3 g): Provides rich, deep chocolate flavor and velvety texture essential for fudgy brownies.
All-purpose flour (1 cup / 125 g): Serves as the base that gives structure and chewiness to the brownie layers.
Baking powder (1 teaspoon): A slight leavening agent to help the brownies rise just enough without losing their dense texture.
Kosher salt (½ teaspoon): Enhances the chocolate’s flavor and balances sweetness in the batter.
Espresso powder (1 teaspoon): Intensifies the chocolate taste with subtle coffee notes for a deeper, more complex flavor.
Unsalted butter (1 cup / 2 sticks / 227 g), room temperature: Adds richness and moisture, creating a smooth brownie batter.
Granulated sugar (2 cups / 400 g): Sweetens the batter and contributes to the chewy texture.
Semi-sweet chocolate chips (1 cup / 168 g): Melts into the batter adding bursts of rich chocolate throughout.
Vanilla extract (1 tablespoon): Brings warmth and depth to the chocolate base.
Large eggs (4), room temperature: Bind ingredients together and provide structure with moisture and richness.
Creamy peanut butter (¾ cup / 193.5 g): Creates the creamy, nutty middle layer contrasting the chocolate layers.
Marshmallow fluff (1 cup / 96 g): Offers a light, airy sweetness and gooey texture layered above the peanut butter.

Instructions

Preheat Oven and Prepare Baking Dish: Set your oven to 350°F (177°C). Line a 9×13-inch ceramic baking dish with parchment paper to prevent sticking and ensure easy removal of the brownies after baking.
Mix Dry Ingredients: In a large bowl, whisk together the cocoa powder, flour, baking powder, salt, and espresso powder. Combining these dry ingredients evenly ensures a consistent flavor and texture throughout the batter.
Melt Butter and Sugar Mixture: In a large saucepan over medium heat, add the butter and sugar. After melting, bring the mixture to a low boil and cook for 2 minutes, reaching about 230°F on a thermometer. This step caramelizes the sugars slightly, adding depth to the brownie flavor.
Incorporate Chocolate Chips and Vanilla: Remove the pan from heat and stir in the semi-sweet chocolate chips and vanilla extract until fully melted. The mixture might look grainy but cooling it for 10 minutes helps it smooth out before adding eggs.
Add Eggs Gradually: Beat in four eggs one at a time, stirring constantly to ensure the batter becomes smooth and glossy without curdling. This builds the structure and richness of the brownies.
Combine Dry Ingredients with Wet Mixture: Fold the dry ingredients into the chocolate mixture until just combined. The batter will be thick and fudgy, perfect for the dense brownie texture desired.
Layer the Brownie Batter and Fillings: Spread half of the brownie batter evenly into the lined pan. Carefully spread creamy peanut butter over this base, then pipe or dollop marshmallow fluff on top using a piping bag or a sturdy plastic bag with the tip cut off. Finish by spreading the remaining batter over the fluff, sealing all layers inside.
Bake the Brownies: Bake in the preheated oven for 28-30 minutes. The edges should be set but the center still slightly soft. Avoid overbaking to keep the fudgy texture and gooey filling intact.
Cool Before Serving: Let the brownies cool completely in the pan. This helps the layers set firmly, making cutting easier and ensuring neat slices with intact marshmallow and peanut butter layers.

You Must Know

Using room temperature eggs and butter helps the batter combine smoothly and bake evenly.
The espresso powder enhances chocolate flavor but won’t make the brownies taste like coffee.
Allowing brownies to cool fully before slicing prevents the gooey layers from mixing.

Storage Tips

Store cooled brownies in an airtight container at room temperature for up to 3 days. For longer storage, refrigerate for up to one week or freeze tightly wrapped for up to 3 months.

Serving Suggestions

Serve Fluffernutter Brownies slightly warmed for an extra gooey experience or chilled for clean, firm slices. Pair with cold milk or a scoop of vanilla ice cream for a decadent treat.

Professional Tips

Use a digital thermometer to ensure the butter-sugar mixture reaches the correct temperature for optimal texture.
Line your pan with parchment paper extending beyond edges to easily lift brownies without breaking.
For a decorative touch, swirl some peanut butter and marshmallow fluff on top before baking instead of layering.

FAQs

Can I use natural peanut butter instead of creamy?: Natural peanut butter may change texture and consistency; creamy peanut butter works best for smooth spreading and even texture.
Is marshmallow fluff necessary, or can I substitute with mini marshmallows?: Marshmallow fluff melts evenly to create a smooth layer; mini marshmallows can be used but may result in uneven texture.
How do I tell when the brownies are done?: Look for set edges and a slightly soft center; a toothpick inserted should come out with moist crumbs but not wet batter.
Can I bake these brownies in a glass dish?: Yes, but reduce oven temperature by 25°F and monitor baking time to prevent over-baking due to glass’s heat retention.
What if I don’t have espresso powder?: You can omit espresso powder without major flavor loss or substitute with instant coffee powder sparingly.
Can I make these brownies ahead of time?: Absolutely! They store well and flavors develop further after resting a day, making them even better when prepared in advance.