Banana Fluffernutter Cake Recipe
The best banana sheet cake frosted with the creamiest peanut butter buttercream, marshmallow fluff and extra peanut butter swirls and/or chopped peanuts!
Ingredients
Banana Cake
- 300 grams (2 1/2 cups) all-purpose flour spooned and leveled
- 10 grams (1 Tbsp) baking powder
- 1/2 tsp fine sea salt
- 1 tsp ground cinnamon
- 300 grams (1 1/2 cups) light brown sugar lightly packed
- 2 large eggs room temperature
- 113 grams (1/2 cup) greek yogurt
- 120 mL (1/2 cup) vegetable oil
- 1 tsp vanilla extract
- 375 grams (about 3 large or 1 1/2 cups) ripe bananas mashed (add a little water to make up the difference to 375g)
- 60 grams (1/2 cup) marshmallow fluff
Peanut Butter Buttercream*
- 200 grams (1 cup) granulated sugar
- 4 large egg whites room temperature
- 227 grams (1 cup) unsalted butter room temperature
- 2 tsp vanilla bean paste or vanilla extract
- 132 grams (1/2 cup) creamy peanut butter more for drizzling on top if you want
- 60 grams (1/2 cup) marshmallow fluff
- handful of lightly salted peanuts roughly chopped
Instructions
Banana Cake
- Preheat the oven to 325F/161C convection. Grease and line a 9x13x2-inch (33x23x6cm) cake pan with baking spray and parchment paper.
- In a medium bowl, whisk together the flour, baking powder, salt and cinnamon. Set aside.300 grams (2 1/2 cups) all-purpose flour, 10 grams (1 Tbsp) baking powder, 1/2 tsp fine sea salt, 1 tsp ground cinnamon
- In a large bowl, whisk together the brown sugar and eggs until they’re smooth. Add the greek yogurt, oil and vanilla extract, whisking them until they’re completely combined.300 grams (1 1/2 cups) light brown sugar, 2 large eggs, 113 grams (1/2 cup) greek yogurt, 120 mL (1/2 cup) vegetable oil, 1 tsp vanilla extract
- Add the bananas to the mixture and mix until they’re fully combined and then fold in the dry ingredients just until the last streak of flour is incorporated.375 grams (about 3 large or 1 1/2 cups) ripe bananas
- Slightly heat the marshmallow fluff in the microwave so that it’s a more runny consistency.60 grams (1/2 cup) marshmallow fluff
- Pour the batter into the prepared pan and dollop the marshmallow fluff on top. Use a knife to swirl it back and forth and then bake for 35 minutes.
- Remove it from the oven and allow it to cool for at least 30 minutes before removing it from the pan to cool completely.
Peanut Butter Buttercream
- Bring a small pot with 1/2 cup of water to a boil and lower the heat to simmer.Place the egg whites and granulated sugar in the bowl of a stand mixer and place the bowl over the simmering water for 5-10 minutes, whisking intermittently until the granulated sugar is completely dissolved.200 grams (1 cup) granulated sugar, 4 large egg whites, 227 grams (1 cup) unsalted butter
- Once the sugar is dissolved, remove the bowl of egg whites from the heat. Use the whisk attachment to beat the egg whites with the sugar. Beat for 7-10 minutes on high speed and then lower the speed to low-medium.
- Slowly add 2 Tbsp of butter in at a time. Wait for the butter to incorporate before adding the next chunk. Once all the butter is added, turn the mixer up to high speed for a few seconds, until it comes together.
- Then use a rubber spatula to scrape the edge of the bowl. Add the vanilla bean paste (or extract) and beat until it’s fully combined.2 tsp vanilla bean paste
- Once the buttercream is done, add in the peanut butter and mix at medium-high speed, just until it’s combined.132 grams (1/2 cup) creamy peanut butter
- Spread the buttercream onto the cooled cake and then gently heat the marshmallow fluff again until it’s a little more of a runny consistency.60 grams (1/2 cup) marshmallow fluff
- Dollop it on top of the buttercream and use an offset spatula to smear it around slightly. Feel free to also melt some peanut butter and drizzle or spread some on top (make sure it's not hot, just a little runny).
- Top with chopped peanuts and enjoy!handful of lightly salted peanuts
Notes
*I've also made a whole egg buttercream for those who don't want to pick between egg yolks and egg whites. I basically just use the EXACT method from French Buttercream but using two whole eggs instead of 4 egg yolks.
*If you are making Swiss meringue buttercream for this recipe and need to use up egg yolks, I recommend making a double batch of my egg yolk chocolate chip cookies!
Nutrition
Serving: 1gCalories: 289kcalCarbohydrates: 35gProtein: 4gFat: 15gSaturated Fat: 6gPolyunsaturated Fat: 9gCholesterol: 36mgSodium: 161mgFiber: 1gSugar: 21g
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