Banana Fluffernutter Cake
The best banana sheet cake frosted with the creamiest peanut butter buttercream, marshmallow fluff and extra peanut butter swirls and/or chopped peanuts!
Banana cake with peanut butter and marshmallow fluff can only mean one thing, it was inspired by a banana fluffernutter sandwich. However, it is in fact superior in cake form.
I didn’t grow up eating fluffernutter because if I wanted something sweet there was always homemade cake in the fridge (thanks mom!). When I finally tried it as an adult, the only thing that made a fluffernutter sandwich better was bananas.
If you haven’t noticed, I LOVE baking with bananas. Some of my favorite cake recipes are my Banoffee Cake and my Banana Pudding Cake and Cupcakes.
How to make Banana Fluffernutter Cake
Fluffernutter is a sandwich that consists of peanut butter and marshmallow fluff. To make a banana cake version I made a one layer banana cake. After I made the batter I swirled in marshmallow fluff. Then it gets frosted with a peanut butter buttercream, more marshmallow fluff on top. The lightly salted peanuts are optional but highly recommended and if you want, you can even add a little drizzle of melted peanut butter to give it more color, texture and flavor.
Banana Cake
A major part of banana cake is the bananas…shocker. Not all bananas are the same size so I highly recommend weighing the bananas after they’re peeled. I suggest using a digital scale for all baking measurements and especially for the bananas and flour.
375g is about 3 medium-large bananas, and if you have a little under (like 350-360g) you can add a couple tablespoons of water. If you don’t have a scale you can also measure it by cup. It’s about 1 ½ cups when it’s all mashed and if you have a little under you can add water.
Peanut Butter Swiss Meringue Buttercream
I went with a Swiss meringue buttercream because I love how silky it is. It’s basically made using a homemade marshmallow fluff and then you add butter, so I thought it was fitting. It’s also less sweet than other frostings and balances out the flavor of the extra marshmallow fluff well. Not to mention, it is sooooo smooth and creamy, especially after adding in the peanut butter.
If you want to experiment with different types of frostings, I recommend my book Frosted. It has 13 base recipes and 60 ways to flavor them and use them in different desserts.
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!
Other ways to bake this cake
I love making cakes interchangeable for sizes so you can bake this cake as a layer cake or even cupcakes. You can make:
- 24 cupcakes
- Three layer 6 inch cake
- Two layer 8 or 9 inch cake from this recipe
- You can also half it and make 12 cupcakes
How to ripen bananas
If you don’t have brown bananas you can cheat and quickly ripen your bananas in the oven. Place them on a cookie sheet in an oven preheated to 300F (149C) and bake them for 10-15 minutes, until they’ve browned. Let them cool and then use accordingly.
How to store Banana Fluffernutter Cake
You can store the frosted cake, covered, at room temperature for 2-3 days. If it’s sliced, cover the cut side with plastic wrap or a cake dome. If you want to refrigerate the cake you can store it covered for up to a week.
You can also store it in the freezer for up to 2 months. To freeze it, slice the cake and place the slices in an airtight container. Then place the container in a freezer bag, squeezing out all the excess air.
I hope you enjoy the best way to eat brown bananas lol. If you have any questions, please comment down below – those will get answered much quicker than email or through social media.
If you’ve enjoyed these, I would very much appreciate a 5-star rating or a review.
As always, have a blessed day and happy baking!
Love, B
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
Tried this recipe?Let us know how it was!
I realise this is quite an old post now but I hope you still see this comment 😅 I’m about to make this in mini loaf cake tins, and I can’t wait! I’m just slightly confused by the temperatures – shouldn’t the convection/fan over temp be lower than the regular oven? I’m used to baking sheet cakes around the 160°C (fan) mark, but you’ve stated a higher temp in this recipe so I’m not sure which to go for! (I currently have my fan oven preheating to around 177°C!) Thanks in advance for any advice 😊
Hi Eleanor, so sorry if I’m late, I hope the cake turned out. All of my ovens tend to burn things on the bottom if I bake them at 350F without a fan. Most fan ovens will adjust 350F to 325F on their own (so if you set it to 350f and put a thermometer in there, it’ll read 325F). If yours doesn’t and/or if you’re used to baking sheet cakes at 325F, then do that!
Hi! I’m really excited to bake this for a co-worker. Was thinking of doing 7-minute frosting instead of the Swiss meringue (they can’t have too much dairy) and swirling the PB in. Do you think I could also use this in place of the fluff in the cake? It’s basically the like fluff but wanted to check! Sorry for the adjustments. Excited to try this. 🙂
Hi Kris, yes it will definitely work, I’ve made the swirls using homemade meringue too. Careful when mixing in the peanut butter swirls on top of the meringue. If you overmix, the fat from the peanut butter can deflate the meringue.