Chocolate, peanut butter and marshmallow fluff. Need I say more?! That's what these fluffernutter brownies are. They have a thick and fudgy brownie base that is baked with peanut butter on top, which is then smothered in homemade marshmallow fluff. They are TOO good.
Have you guys ever had a fluffernutter sandwich? If not, you need to go into your kitchen right now and make one. It is SO good. It is basically a layer of peanut butter and a layer of marshmallow fluff smushed together between two pieces of bread. The saltiness from the peanut butter and sweetness from the fluff makes it the PERFECT snack.
The fluffernutter sandwich is where the inspiration for these brownies came from. It is a thick, fudgy brownie (the same recipe as my Iced Fudge Brownies), baked with a peanut butter layer on top, then smothered in homemade marshmallow fluff.
Ingredients for fluffernutter brownies
If you need to run to the grocery store, here is your shopping list:
- Instant coffee granules + water (optional)
- Unsalted butter: unsalted butter is my favorite to use in baked goods because you can control exactly how much salt goes into your recipe. We use a lot of butter in this recipe, so make sure to splurge on the good stuff!
- Powdered sugar: powdered sugar is the sugar of choice because it is fine enough so it can dissolve in the butter which is key for that crackly top. We also use powdered sugar in the homemade marshmallow fluff.
- Eggs: eggs add moisture and bind all of the ingredients together. We also need egg whites for the homemade marshmallow fluff. So we need a total of 8 eggs - yikes.
- Vanilla extract
- All purpose flour: all purpose flour is the flour of choice for these brownies. It provides the perfect texture!
- Cocoa powder: cocoa powder adds the rich chocolatey flavor that is expected in a brownie.
- Cream of tartar
- Vanilla extract
- Make the brownie batter and bake for 40 minutes. Let cool completely.
- While the brownies are cooling, make the homemade marshmallow fluff.
- Top the brownies with the fluff, toast with a baking torch if you have one, slice and enjoy!
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- ¾ cup (94 grams) all purpose flour
- 1 ½ cups (120 grams) cocoa powder unsweetened regular cocoa powder or dutch processed cocoa powder works!
- ¾ teaspoon salt
- 1 teaspoon instant coffee granules + 1 teaspoon water optional
- 1 ¼ cups (283 grams) unsalted butter melted
- 4 ¼ cups (510 grams) powdered sugar
- 4 eggs room temperature
- 1 teaspoon vanilla extract
- ½ cup (130 grams) peanut butter I like to use creamy!
Homemade Marshmallow Fluff
- 4 egg whites
- 1 cup (120 grams) powdered sugar
- ½ teaspoon cream of tartar
- ½ teaspoon vanilla extract
- Preheat oven to 350 degrees Fahrenheit (177 degrees Celsius) and line a 9x9 inch pan with parchment paper. Set aside.
- I suggest having all the ingredients out and measured to make this process easier.
- In a bowl, whisk together the flour, cocoa powder and salt. Set aside.
- If using the coffee, combine the instant coffee granules and water in a small bowl until the granules are completely absorbed. This is optional but recommended - the coffee really deepens the chocolate flavor.
- In a separate, microwave-safe bowl, combine the butter and powdered sugar. Melt the two together in the microwave in 30 second increments, whisking in between each increment. I typically microwave it 4-5 times. Whisk them together until completely smooth and the powdered sugar is dissolved in the butter. It should almost look like melted white chocolate. You can also melt them together on the stove.
- Meanwhile, whip your eggs. Crack the eggs in the bowl of a stand mixer fitted with the whisk attachment (or a medium sized bowl if using a handheld mixer), and beat them on medium speed for 4-5 minutes until they are a paler yellow color and foamy.
- Once the eggs are done whipping, pour in the hot butter/sugar mixture. Whip them together on medium speed for two minutes. Add the vanilla and coffee mixture (if using) and whip until combined.
- Add the flour, cocoa powder and salt and fold together (not whisk) until a batter forms. Whisking will knock out all of the air you just added by whipping the eggs. Pour the batter into the prepared pan.
- Dollop the peanut butter onto the batter and swirl it into the top with a knife or toothpick.
- Bake for 40-45 minutes (begin checking at 35 minutes - bake times vary depending on your oven). The edges will be set and a toothpick inserted into the center should come out with a few moist crumbs.
- Remove the brownies from the oven and let them sit in the pan until completely cool.
Homemade Marshmallow Fluff
- Fill a sauce pan with about two inches of water and bring it to a gentle simmer. Separate the yolks from the egg whites and make sure NONE of the yolk gets into your egg white mixture.
- In a heat proof bowl, place the egg whites, powdered sugar and cream of tartar. Place the bowl on the sauce pan over the simmering water but do NOT let the bottom of the bowl touch the simmering water. You can also use a double boiler if you have one.
- Continuously whisk while the mixture heats up. It will start out thick, and the powdered sugar may be clumpy (this is okay!), it will thin out and the clumps will dissipate as you keep on whisking. Whisk for about 4-5 minutes until the mixture is thin and frothy on top - if you have a thermometer, it should be around 160 degrees Fahrenheit.
- Remove from the heat and add the vanilla extract. Using a handheld mixer or in the bowl of a stand mixer fitted with the whisk attachment, beat on high speed for 5-6 minutes until luscious, puffy, stiff peaks form.
- Once the brownies are completely cool, top with the marshmallow fluff. If you have a baking torch, I highly suggest toasting the marshmallow fluff topping a bit - it LITERALLY tastes like a fireside marshmallow. Slice and enjoy!
Tried this recipe? Make sure to rate and review and tag @sturbridgebakery on Instagram!