Banana Cake with Brown Sugar Buttercream

Simplicity is the
ultimate sophistication.
— Leonardo Da Vinci

Okay everyone... I have a secret to tell you... I, Bella Christensen, ate banana baby food until I was 4 years old. There. I said it. Don’t ask me why, I just loved it. And it’s not as if my mother went out of her way to buy it for me, I have two younger siblings so it was just always around. I remember eating it as a snack almost daily because i thought it was THAT good. And I didn’t like any of the other flavors, only banana. And although I no longer eat jars of banana baby food, I still love bananas and banana-y desserts. 

One of my all time favorite banana desserts is a classic Banana Bread (that  counts as dessert right?). I love using my overripe and blackened bananas because every time I buy bananas it seems as if 3-4 of them inevitably turn out that way. I don’t know, it must be some sort of banana law or something. Regardless, there’s no reason those should go to waste! I always use my overripe bananas either by whipping up a quick banana bread or placing them in an airtight bag and freezing them until I want to bake with them. And now I have a new favorite way to use them and it is for this Banana Cake with Brown Sugar Buttercream

One of my all time favorite banana desserts is Banana Cream Pie, which I made into a tart version a while back (get that recipe here). There is something so delicious about freshly sliced bananas paired with a graham cracker crust, vanilla pastry cream, and fresh whipped cream. Mmmm. However, that recipe requires fresh (not over ripe) bananas so I needed a new way to use those older ones. Now I love a classic banana bread but I felt like it was always missing something. So I decided to transfer the classic banana bread into an ultra moist and flavorful cake with a silky smooth brown sugar buttercream.

Now the best thing about this recipe is that it is super quick and easy to make and requires minimal ingredients. Also, it’s made in a sheet pan so there’s no need for multiple cake pans or to stack and frost a three layer cake. You can chose to leave the cake in the pan and frost and slice in there or you can transfer the cake to a serving platter for a prettier presentation. I love sheet cakes because they are so easy and they make transporting for events/parties a breeze. Whenever I want to bring something in to work or for smaller occasions I always opt for a sheet cake because they are just as delicious as an elaborate three-tiered cake and are MUCH easier to handle.

Now on to the ingredients. This cake, like I mentioned above, uses minimal ingredients, most of which you probably already have in your pantry. The cake itself includes the usual baking ingredients (flour, sugar, baking soda, salt, etc.) and a few other ingredients that really take this cake from being ordinary to AMAZING. Here they are:

  • Over-ripe Bananas: I mean the bruised as heck, blackened, squishy bananas that everyone refuses to touch. Yep, those ones. NEVER throw those away you guys. They work perfectly for this Banana Cake because they are ultra sweet and the banana flavors are very intense when they get that ripe. They also provide tons of moisture for the cake itself. This recipe is pretty full proof thanks to the bananas and their moisture levels. As soon as my bananas get super dark, I put them in a ziplock and freeze them until I’m ready to bake. The night before I’m going to use them, I let them thaw in the fridge and then remove the peels and mash them with a fork and measure out what I need.

  • Buttermilk: Using buttermilk in this recipe does a couple things. It adds a subtle yet pleasing tang/acidity to baked goods recipes which is especially important in a recipe like this since the bananas (and sugar) are so sweet. It also does a lot for the actual structure of the cake. Using buttermilk in baking recipes will help break down long strands of gluten which results in a super tender cake. It also is another ingredient that adds extra moisture! And I know that there are lots of tips and tricks out there on how to make buttermilk substitutes (milk + vinegar or lemon juice) but I really have not had much luck with those alternatives. I find that the results vary wildly and my baked goods never quite work. I highly recommend just purchasing a carton of real buttermilk at the grocery store. If you’re worried that you’ll have tons of leftover buttermilk, don’t worry, you can make my Best Blueberry Pancakes (trust me, you need this recipe in your life!)

  • The Spices: I kept things pretty simple here. Cinnamon and a tiny bit of nutmeg. This cake is not intended to be a spiced cake and it doesn’t taste like one either. The spices are very subtle and really are there to compliment the banana flavor. If you want more of a “spiced” cake taste, feel free to add another teaspoon of cinnamon and another pinch of nutmeg. Heck, throw in 1/4 teaspoon of cardamom!

  • The Walnuts: Now I love putting walnuts in my banana bread so I felt it necessary to add them to my Banana Cake too. I like the texture that they add and to be honest, I just love walnuts! So, if you are allergic or don’t have any on hand, feel free to omit them. It won’t ruin the cake by any means. If you decide to use them I highly recommend blitzing them in a food processor until they are about the size of peas (maybe even a little smaller) so that you aren’t getting huge pieces of walnuts throughout the cake. I like blitzing them because I think the texture is better that way and the walnuts actually get more evenly dispersed throughout the cake.

I would also be remiss if I didn’t talk about the Brown Sugar Swiss Meringue Buttercream before ending this post. If you’ve never had swiss meringue buttercream then you must try it now. Basically you start out by making a quick swiss meringue by cooking egg whites and sugar, in this case brown sugar, over a double boiler until the eggs are cooked. You then whip it into a stiff meringue and then slowly add in softened butter once it’s cooled down. The result is a silky smooth, perfectly sweet, perfectly butter-y, and has notes of caramel from the brown sugar that pairs perfectly with the Banana Cake. Trust me, you will constantly be scooping out personal taste tests once you make this frosting because it is THAT good.

So, if you have a bunch of yucky old bananas sitting in your fruit bowl or a frozen bag of them like me then you need to make this Banana Cake with Brown Sugar Buttercream ASAP! It’s such an easy and delicious recipe and couldn’t be a more perfect way to use fruit that is otherwise inedible. I’m a big believer in wasting as little as possible so this recipe is one way that I do that.

If you try this recipe or any other from the blog please share your feedback, questions, and/or photos with me, I would love to hear from you! Happy baking everyone! Xx

Banana Cake with Brown Sugar Buttercream


For the Cake

  • 1 ½ Cups Super Ripe Bananas (3-4 Bananas) *see note

  • 3 Cups All Purpose Flour

  • 1 Teaspoon Baking Powder

  • 1 Teaspoon Baking Soda

  • 1 Teaspoon Kosher Salt

  • 1 Teaspoon Cinnamon

  • ¼ Teaspoon Ground Nutmeg

  • 1 Cup Finely Ground Walnuts *see note

  • 12 Tablespoons Butter, room temperature

  • 1 Cup White Sugar

  • ½ Cup Light Brown Sugar, tightly packed

  • 3 Large Eggs, room temperature

  • 1 Teaspoon Vanilla Extract

  • 1 ½ Cups Buttermilk, room temperature

For the Brown Sugar Swiss Meringue Buttercream (recipe adapted from Serious Eats)

  • 3 Ounces Egg Whites

  • 5 ½ Ounces Light Brown Sugar

  • ½ Teaspoon Kosher Salt

  • ⅛ Teaspoon Cream of Tartar

  • 32 Tablespoons Butter, room temperature


Make the Cake:

  1. Preheat oven to 350℉. Spray a 9x13” baking pan with cooking spray and line with parchment paper— I cut a sheet of parchment paper that fits the length the pan perfectly and have a two inch overhang on the long sides (so that you can lift the cake out of the pan once it’s baked).

  2. In a bowl, mash up the bananas until you have a smooth paste without any large lumps. Set aside.

  3. In a large bowl, add the flour, baking powder, baking soda, salt, cinnamon, nutmeg, and ground walnuts and whisk until evenly combined. Set aside.

  4. In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, white sugar, and brown sugar on medium-high speed until light and fluffy— a full five minutes. With the mixer on low, add in the eggs one at a time, incorporating each one fully before adding the next. Once all of the eggs are added, stop the mixer and scrape down the sides and bottom of the bowl and mix on high speed for 20 seconds.

  5. Whisk together the vanilla extract and buttermilk into a large measuring cup. Now, add the dry and wet ingredients in three additions, alternating between the wet and the dry, mixing just enough to combine in between each addition. Once all of the wet and dry ingredients have been added, stop the mixer and scrape down the sides and bottom of the bowl. Mix the batter on medium-high speed for another 15-20 seconds or just until everything comes together— do NOT over mix!

  6. Transfer the batter to the prepared baking pan and level it out with an offset spatula to make sure the batter is in an even layer. Bake for 35-40 minutes, checking halfway in between, until a toothpick inserted comes out clean. Remove the cake from the oven and let cool completely.

Make the Brown Sugar Buttercream

  1. In a large bowl, whisk together the eggs whites, brown sugar, salt, and cream of tartar.

  2. Bring a medium-sized saucepan filled with about two inches of water to a simmer over low-medium heat. Place the bowl over the pan of water— making sure the bottom of the bowl is NOT touching the water or else it will cook the eggs!). Cook the egg + sugar (meringue) mixture until there are no more sugar granules and it reaches approximately 185℉ on a thermometer.

  3. Transfer the meringue mixture to the bowl of a stand mixer fitted with the balloon whisk attachment and beat on high speed until the meringue is glossy, holds stiff peaks, and it is room temperature. It is VERY important for the meringue to be room temperature or else it will melt the butter when you add it in.

  4. Next, with the mixer on medium speed, add in the butter about 1 tablespoon at time, mixing well in between each addition, until all of the butter is added and the buttercream is fluffy. Stop the mixer and scrape down the sides and bottom of the bowl and mix again on medium speed to ensure that everything is fully combined.

To Assemble

  1. Remove the cake from the pan using the overhang of parchment paper and transfer it to a serving plate or cutting board. Place large dollops of the brown sugar buttercream on the top of the cake and use a large spoon or offset spatula to spread the frosting all over the top of the cake, creating “swooshes” in the buttercream for a rustic look like I did.

  2. OR you can leave the cake in the pan and frost it directly in there following the steps as #1. This is a good option if you need to transport the cake for an event/party.

  3. Whichever way you choose, all you have to do now is slice and enjoy!

This cake is best eaten the day it’s made but it can be kept for 4-5 days in the fridge covered with plastic wrap.


  1. The Bananas: you want to use reallyyyyy ripe bananas here. I’m talking the bruised/blackened ones that no one else will touch. They are perfect for banana cake and bread because they are ultra sweet at that point. When my bananas start to turn brown and soft I put them in a ziplock bag and freeze them. Then when I’m ready to use them I let them thaw out for a couple hours and mash them up.

  2. The Walnuts: The texture of the walnuts can be tricky to get sometimes. You don’t want huge half pieces of walnuts in the cake because 1. the texture will be all wrong and 2. there won’t be an even distribution of them throughout the cake. So, I like to put them in my mini food processor (but you could put them in a ziplock bag and smash them with a rolling pin) and pulse until they are about the size of peas. Some will be smaller than that and that’s okay. You really just don’t want them any bigger than that. It is also okay if some of them have turned almost into powder— it’ll just add walnut-y flavor! And if you’re not a fan of walnuts, feel free to swap for a different nut (pecans) or leave them out all together.