Delish Fluffernutter Brownies
This is my take on the ultimate childhood-meets-adult dessert: fudgy brownies studded with ribbons of creamy peanut butter and gooey marshmallow fluff. The result is sticky, decadent, and gloriously nostalgic—all the flavors of a fluffernutter sandwich, but rich, chocolatey, and perfectly portioned for sharing (or not).
My family goes a little wild for these. My husband will volunteer to “test” a slice about as often as I’m willing to let him, and our kid calls them “chocolate clouds” because of the marshmallow pockets. They became a staple after an impromptu baking afternoon where I combined two pantry favorites and ended up with a pan that disappeared in a single evening—now I make them whenever I want a guaranteed crowd-pleaser and a comforting hit of nostalgia.
Why You’ll Love This Delish Fluffernutter Brownies
– The contrast of dense, fudgy brownie and soft marshmallow swirl keeps every bite interesting.
– Peanut butter adds savory balance so the sweetness never feels one-note.
– Easy to assemble with pantry-friendly ingredients—no special equipment required.
– Great for feeding a crowd or slicing small for parties; they travel and freeze well.
– Customizable: swap in crunchy peanut butter, add chopped peanuts, or drizzle with extra chocolate.
Behind the Recipe
This recipe grew out of late-night cravings for something both chocolatey and nutty. Over several batches I learned that a glossy, slightly underbaked center gives the best fudgy texture, and that swirling rather than fully mixing the peanut butter and fluff preserves their distinct pockets of flavor. A few small fails taught me to resist overmixing the batter once the flour goes in, and to dollop the marshmallow last so it doesn’t fully dissolve into the chocolate. The little touches—using a spoon to drag the swirl into pretty patterns, cooling the pan long enough to cut clean squares—make it feel homemade and deliberate.
Shopping Tips
– Baking Basics (Flour/Sugar/Leaveners): Use all-purpose flour for classic brownies; measure by spooning into the cup and leveling to avoid a dry, cakier result.
– Chocolate: Choose a good-quality bittersweet or semisweet chocolate for melting—it makes a noticeable difference in depth and fudginess.
– Nuts & Seeds: Pick a creamy peanut butter labeled “stir” or smooth for easier swirling; crunchy works too if you want texture.
– Eggs: Use large, room-temperature eggs for better incorporation and a silkier batter.
– Specialty Item: Marshmallow creme/Fluff is the signature—buy the real thing for the best gooey pockets, and keep it chilled until you’re ready to use.
Prep Ahead Ideas
– Measure dry ingredients and store them in a sealed container or zip bag in the fridge a day ahead to speed assembly.
– Melt chocolate and butter, then cool and store in the fridge in an airtight jar for 24 hours; rewarm gently before using.
– Prepare the peanut butter swirl by thinning a portion with a tablespoon of milk or oil so it’s ribbon-ready; keep covered in the fridge and bring to room temperature before swirling.
– If you want no-stress entertaining, bake the brownies a day ahead and store them in an airtight container; the flavors mellow and deepen overnight.
Time-Saving Tricks
– Microwave the chocolate and butter in short bursts, stirring between intervals to melt quickly without scorching.
– Use a handheld mixer or whisk to combine wet ingredients, then fold in dry ingredients by hand to avoid overworking the batter.
– Line the pan with parchment so you can lift the whole slab out to cool and slice—quicker and cleaner than trying to cut in the pan.
– Keep your swirl tools simple: a butter knife or offset spatula makes perfect marbling without fuss.
Common Mistakes
– Overbaking: Brownies continue to set as they cool—pull them when a toothpick comes out with a few moist crumbs, not completely dry. If overbaked, reheat briefly and serve with cream or ice cream to add moisture.
– Mixing the swirl in too aggressively: If you overmix, the peanut butter and fluff will disappear into the batter; dollop and gently drag for distinct ribbons.
– Using overly dry peanut butter: Old or oil-separated jars can make the swirl clumpy—stir well and, if needed, thin with a teaspoon of neutral oil.
– Cutting too soon: Let the pan cool at least 30–45 minutes, then chill briefly for neat squares; a warm knife (wiped between cuts) makes cleaner slices.
What to Serve It With
These brownies are lovely on their own, but here are a few pairings that elevate them:
– A scoop of vanilla or salted caramel ice cream for contrast and temperature play.
– A dusting of flaky sea salt to highlight the chocolate and peanut butter.
– Fresh berries or a quick berry compote to cut sweetness with bright acidity.
– Coffee or a rich milk to balance the richness.
Tips & Mistakes
The biggest tip I can offer is to resist the urge to overbake—fudgy is the goal. If your marshmallow pockets deflate while baking, it usually means the pan was too hot or the fluff was too thin; next time dollop thicker spoonfuls and swirl lightly. If slices crumble, chill them a bit longer before cutting.
Storage Tips
Store in airtight containers in the fridge. It reheats beautifully, but if you sneak a bite cold straight from the container, it still works.
For longer storage, freeze individual squares between layers of parchment for up to 3 months and thaw at room temperature.
Variations and Substitutions
– Swap crunchy peanut butter for smooth to add more texture, or use almond butter for a different nutty profile (flavor will change noticeably).
– For a less-sweet option, use dark chocolate or reduce sugar slightly in the batter.
– To make them extra decadent, fold in chopped peanuts or a handful of chocolate chips.
– Gluten-free option: replace the flour with a 1:1 gluten-free baking blend and don’t overmix.
Frequently Asked Questions
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Delish Fluffernutter Brownies
Ingredients
Main Ingredients
- 1 cup unsalted butter melted
- 2 cups granulated sugar
- 4 large eggs room temperature
- 1 cup unsweetened cocoa powder
- 1 cup all-purpose flour
- 1 teaspoon baking powder
- 0.5 teaspoon salt
- 0.5 cup smooth peanut butter
- 1 cup mini marshmallows or marshmallow fluff
Instructions
Preparation Steps
- Preheat your oven to 350°F (175°C) and grease a baking dish. In a large bowl, whisk together the melted butter and sugar until combined. Then, add the eggs one at a time, mixing well after each addition. Stir in the cocoa powder, flour, baking powder, and salt until the batter is smooth.
- Pour half of the brownie batter into the prepared dish and spread it evenly. In another bowl, mix the peanut butter with a bit of the remaining brownie batter until combined. Dollop this creamy mixture over the brownie layer and swirl it gently with a knife.
- Top the swirled mixture with marshmallows, then pour the remaining brownie batter over everything, smoothing it out. Bake in the preheated oven for about 30 minutes or until a toothpick comes out with a few moist crumbs.
- Once baked, allow the brownies to cool completely before cutting them into squares. Enjoy your deliciously gooey treats with a glass of milk!