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
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.