Peanut Butter Banana Cake

What could be better than banana bread? Peanut Butter Banana Cake, duh.

I quickly became absolutely obsessed with these browned butter rice krispy treats that I couldn’t help but dream up another way to use the combination of peanut butter and marshmallow fluff. It got me thinking… what would be another great addition to the pair?? Bananas, of course.

What is Peanut Butter Banana Cake?

I made the base of this recipe (the banana cake) a long long time ago, but I paired it with a cinnamon cream cheese frosting. Don’t get me wrong, those 2 together are absolutely dynamite, and it’s kind of similar these pumpkin cake cupcakes, but I’m a girl who spreads some peanut butter on a banana and is happy as can be. So obviously I had to make a cake out of that.

The best part of this cake? We’re making the base of it in 1 bowl. Hallelujah. No need to measure out the dry ingredients and then add them to the wet ingredients, it truly couldn’t be easier. If you’re looking for another one-bowl cake, check out this vanilla cake or this chocolate cake! I do ask you to mash the bananas in a separate bowl though, because it’s just easier that way.

This cake is incredibly moist and the frosting + the marshmallow fluff is an absolute match made in heaven. We go over to Noah’s parents for dinner usually once a week, and I always bring whatever recipe I’ve been working on recently. Well, I brought the banana cake and it was a hit! No one can pass up a moist, tender cake with a deliciously smooth frosting on top.

Some equipment you may need…

These will all be super helpful as you bake this banana peanut butter cake 🙂

8-inch square pan: I love these from USA pan because they’ve got nice slick corners and they’re a light color, but use what you have!
Stand mixer: this is the one I have and I love it! I’ve had it for years now and I’ve never had any trouble with it. You definitely don’t “need” a stand mixer for this banana peanut butter cake recipe, but it sure does make life a lot easier.
Offset spatula: the best little utensil for almost any baking project. I find myself reaching for this one allll the time in the kitchen. It’s so helpful to use when spreading the frosting onto the cake.
Measuring cups/spoons: I’ve been linking these in all of my posts because I love them SO much! They are beautiful and look just like some other expensive ones on the market (but wayyy cheaper).
Mixing bowls: I love these glass mixing bowls from Amazon. They’re especially perfect for food photography.

Ingredients for Peanut Butter Banana Cake

Very ripe bananas – just like my favorite banana bread – we’re talking all the brown spots, friends. An overripe banana is a sweet banana, and we want a perfectly sweet peanut butter banana cake so don’t be afraid of those brown spots!
Unsalted butter – I love adding butter to my cake bases because while it may not bring as much moisture to the table, it adds a whole lot of flavor to this banana and peanut butter cake.
Vegetable oil – in addition to the butter, we’re going to add some vegetable oil to the mix so we end up with as moist of a banana cake as possible. No one likes a dry cake, and oil is our best friend when it comes to a moist cake.
Granulated sugar – we’re going to use both granulated and brown sugar for this recipe
Light brown sugar – don’t have brown sugar? Just add the exact amount of granulated that you would brown sugar and you’ll be just fine. I promise your banana cake with peanut butter will taste just as good!
Large eggs – just make sure they’re at room temperature as that will help to incorporate them into the batter much easier.
Sour cream – a cake is always better with sour cream, and especially this banana cake with peanut butter frosting
Vanilla bean paste – now is not the time for artificial vanilla. Since this cake is all about the vanilla, I suggest using a high quality one!
Baking powder – this will be our chemical leavening agent in this cake (what makes the cake rise).
Kosher salt – I use Diamond Crystal Kosher Salt always. This is also something I’d suggest using as the sodium content can vary across brands.
All-purpose flour – I almost always use King Arthur flours, because I think consistency is important when developing recipes. Protein content can vary between brands, so I’d recommend sticking with King Arthur as well!
Cream cheese – an essential ingredient in the frosting, and pair so well with the cream cheese we’ll add as well.
Creamy peanut butter – I love peanut butter frostings, and if you do too you should check out this chocolate cupcake recipe (topped with a HEAP of pb frosting). I always use Jif peanut butter when baking and just eating, to me it has the best flavor!
Powdered sugar – another essential ingredient for our frosting.
Marshmallow fluff (optional) – ok like I said this is completely optional but MAN does it go a long way in the actual appearance of the cake! I was inspired by these peanut butter rice krispie treats I made a few months back and I couldn’t help but do a similar look here!

Possible ingredient substitutions

Butter vs vegetable oil in a cake

Butter is often added to a cake or cupcake recipe because it’s a huge flavor carrier. If you don’t have butter on hand, though, you can just add the same amount in oil that you would butter.

Vegetable oil vs Canola oil

Canola oil and vegetable oil are very similar, they’re both unscented, relatively flavorless oils, so you can swap them 1:1 in any baking recipe.

My Kitchen Tips:

Use OVERripe bananas.

You guys know the drill from my tried and true banana bread recipe. The longer a banana sits, the more it ripens. And the more it ripens, the sweeter it becomes. This cake doesn’t rely on the sweetness of the bananas, but it makes the flavor much, much better. Bananas taste more like bananas when they’re perfectly ripe. I like for mine to have quite a few brown spots on them before I use them in almost any baking recipe.

We’re using 1 bowl for the base.

Could this peanut butter banana cake get any easier?!? I had this thought months ago when I was mixing up some dry ingredients to go in a cake recipe: why not just beat in the baking powder and salt before you add the flour? I’m still not 100% sure if it really makes a difference or not, but I’ve been skipping the mixing of the dry ingredients ever since. It’s so much easier to just beat in the leavening agent and salt before adding the flour, that way it still gets incorporated like you want it to. This is super similar to my Super Moist One-Layer Chocolate Cake, all made in one bowl and so easy.

Do not overbeat your batter.

Just like my Vanilla Cake Recipe! This is a cake must. If you over beat your batter, you’ll cause too much gluten to form in the flour (resulting in a tough cake), and you’ll also whip too much air into the batter. I like to beat my flour in just until the small streaks go away.

Recipe FAQs

How to Store Peanut Butter Banana Cake

You can store this cake in an airtight container in the refrigerator for 3 to 5 days. When you want a slice or 2, just set them out at room temperature for a couple hours before you serve them.

Can I make anything ahead?

Yes! You can make the whole cake ahead, just wrap the whole thing in plastic wrap when it’s completely cooled and place it in the refrigerator. You can do the same with the peanut butter cream cheese frosting, make it ahead and store it in an airtight container in the refrigerator for up to 1 week.

You can also make this way in advance and freeze both the peanut butter banana cake and the frosting. Just do as described above, only place everything in the freezer instead.

What other frostings can I use?

I love swapping up my frostings, and if you do too you should try this Chocolate French Buttercream or this Swiss Meringue Buttercream on top of the cake instead. Both will require just a little bit more effort, but it will be worth it in the end!

I hope you all love this peanut butter banana cake as much as I (and my family) does. Feel free to always reach out to me via email (sarah@sarahsdayoff.com), through my Instagram DMs (@sarahsday0ff), or by leaving a comment on one of these posts. I’m happy to answer any questions I can!

If you make this recipe be sure to tag me @sarahsdayoff so I can see them!

“If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness.” -1 John 1:9-

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