Banana and chocolate are such a great flavor combination! My moist banana cake with chocolate frosting is filled to the brim with banana flavor and topped with a simple frosting. The addition of sour cream to the cake batter ensures the recipe comes out of the oven extra moist and fluffy every time. It's the perfect way to use up overripe bananas with a great recipe that everyone is sure to love!
If you're craving something more low-key, don't miss my reader-favorite banana snacking cake — or for more single-pan desserts in general, browse all my quick and easy sheet cake recipes.
Disclosure: As an Amazon Associate, I earn from qualifying purchases.
Why this one's a keeper
This is a one-layer banana cake with a thick layer of chocolate frosting — built for snacking, not for a special occasion. My salted caramel banana cake gets a lot of love, so I built this moist sour cream banana cake as the chocolate-lovers' version. It's also just a genuinely great way to use up bananas that have gone past the point of eating out of hand.
Brown the butter. It takes an extra five minutes and it's the single biggest flavor upgrade in this recipe — browning caramelizes the milk solids and gives the cake a nutty, almost toffee-like depth that plain melted butter can't touch.
Ingredients & swaps
- Instant coffee (optional): doesn't make the frosting taste like coffee — it deepens the chocolate flavor. Skip it if you'd rather not.
- Bananas: the riper (spottier) the better — that's where the flavor and sweetness live. Short on time? Ripen bananas in the oven instead of waiting.
- Sour cream: full-fat, for moisture and a slight tang that balances the sweetness. Plain full-fat Greek yogurt works in a pinch.
- Butter, browned: see the skim stopper above — how to brown butter if you haven't done it before.
- Eggs: room temperature, so they incorporate smoothly instead of seizing the browned butter.
- Chocolate for the frosting: a baking bar (Ghirardelli, Baker's, and Scharffen Berger are my go-tos), not chocolate chips — chips have stabilizers that keep the frosting from going silky-smooth.
How I make it
The short version: brown the butter and let it cool slightly, whisk your dry ingredients, stir your wet ingredients together, combine, fold in the browned butter, and bake in an 8×8 pan for about 25 minutes.
Full ingredient amounts and step-by-step photos are in the recipe card below.
Pro tips from my kitchen
- Bananas too firm? Use the oven trick above — it's faster than waiting on the counter and works just as well for flavor.
- Want a layer cake instead? Double the recipe, split it between two 8-inch rounds, and bake until a toothpick comes out with just a few moist crumbs.
- Make-ahead: the unfrosted cake freezes well for up to 3 months. Frost it fresh the day you're serving it.
Frosting too soft to spread cleanly? Chill it for 10 minutes before you frost — dark chocolate frosting firms up fast in the fridge but stays easy to spread once it's cooled slightly, unlike a plain buttercream.
FAQs
How many bananas do I need? About 2–3 medium bananas, but measure by volume, not count — you want 1 cup mashed, since banana size varies a lot.
Can I make it chocolate chip instead? Fold in ½ cup semi-sweet chocolate chips right before the batter goes into the pan.
What's the difference between banana cake and banana bread? Cake gets frosted and has a lighter, more tender crumb; bread is denser and usually goes unfrosted. Same base flavors, different textures.
Step-By-Step
Like this recipe? Follow me on Pinterest for lots more recipes just like this one! And don’t forget to pin this recipe for later by clicking on one of the images below the recipe. Or, click on any of the images in this post to save to Pinterest.
FOR ALL MY FAVORITE BAKING TOOLS INCLUDING THOSE USED TO MAKE THIS RECIPE, CHECK OUT MY BAKING RESOURCES PAGE!
More recipes
Did you enjoy a KICKASS BAKER recipe? Please share a comment and leave a 5 Star ⭐️⭐️⭐️⭐️⭐️ Rating on this recipe! We appreciate you sharing your feedback!
Ingredients
- brown butter from ½ cup unsalted butter (113 g)
- 1 ½ cups all-purpose flour
- ¼ cup granulated sugar
- ¾ teaspoon baking soda
- 1 teaspoon salt
- 1 cup mashed bananas 2 to 3 very ripe bananas
- ¼ cup full-fat sour cream
- 2 tablespoons dark brown sugar packed
- 2 large eggs room temperature
- 1 teaspoon vanilla extract
Chocolate Frosting
- 8 ounces dark chocolate baking bar not chocolate chips if you can avoid it
- 1 cup unsalted butter room temperature
- 2 tablespoons heavy cream
- 1 teaspoon vanilla extract
- 3 cups powdered sugar
- 1 tablespoon instant coffee granules + 3 teaspoons hot water optional
Instructions
- Preheat the oven to 350 degrees F. Line an 8×8 inch baking pan with parchment paper letting the two long ends hang over the edges by at least 2 inches. Butter the top of the parchment and set aside.
- Melt the butter in a small saucepan, cooking and stirring until the butter is just browned (be careful not to cook too long or it’ll burn). Set aside to cool slightly before adding to the cake batter. brown butterbrown butter
- In a large bowl, whisk together flour, granulated sugar, baking soda and salt. 1 ½ cups all-purpose flour1 ½ cups all-purpose flour, ¼ cup granulated sugar, ¾ teaspoon baking soda, 1 teaspoon salt
- In a separate bowl, whisk together the bananas, sour cream, brown sugar, eggs and vanilla. Add the wet ingredients to the dry ingredients, mixing just until combined (you should still see a few dry spots of flour). Whisk in the browned butter, stirring just to combine. Do not overmix. 1 cup mashed bananas1 cup mashed bananas, ¼ cup full-fat sour cream, 2 tablespoons dark brown sugar , 2 large eggs , 1 teaspoon vanilla extract, brown butter
- Scrape the batter into the prepared baking pan and smooth the top with an offset spatula or butter knife.
- Bake until the top springs back when lightly pressed in the center, and a toothpick inserted in the center comes out clean, about 25 minutes. Let cool completely.
- Meanwhile, prepare the Chocolate Frosting. Chop the chocolate and place it in a heatproof bowl over a pan set over simmering water (be sure the bowl is not touching the water so your chocolate does not scorch). Stir the chocolate until just melted and set aside until cooled to room temperature. 8 ounces dark chocolate baking bar8 ounces dark chocolate baking bar
- In the bowl of an electric mixer fitted with the paddle attachment, beat the butter on medium-high speed until light yellow and fluffy, about 3 minutes. Add the heavy cream and vanilla and continue beating for 3 minutes. 1 cup unsalted butter1 cup unsalted butter , 2 tablespoons heavy cream, 1 teaspoon vanilla extract
- Turn the mixer to low, gradually add the powdered sugar, then beat at medium speed, scraping down the bowl as necessary, until smooth and creamy.3 cups powdered sugar3 cups powdered sugar
- In a separate bowl, dissolve the coffee in 2 teaspoons of the hottest tap water. 1 tablespoon instant coffee granules1 tablespoon instant coffee granules
- With the mixer on low speed, add the chopped chocolate and dissolved coffee to the butter/sugar mixture and beat until blended and smooth.
- Once the cake is completely cooled, frost the cake (you may not use all the frosting). Slice into 16 squares and serve.
Notes
- Store leftover cake in the refrigerator for up to 4 days
- Banana cake without frosting may be frozen for up to 3 months
- If you have leftover frosting, store it in a jar with a tightly fitting lid in the refrigerator for up to 2 weeks or in the freezer for up to 1 month. Defrost at room temperature and give a good stir with a spatula before using.
Nutrition
Comments
Evelyn Pfeifer says
This is to die for!! Best banana cake Ever 😻😻 I didn't even ice it and it was fabulous.
Kimberlee Ho says
Wonderful to hear!