If you’re looking for a way to use up ripe bananas and your sourdough discard, this fluffy banana cake is it. It’s soft and light—more like a banana sheet cake than banana bread—and topped with the dreamiest whipped brown butter cream cheese frosting that tastes like salted caramel cheesecake. I’m not exaggerating when I say this cake disappears fast in my house (and I live with three hungry boys, so that says a lot).
Whether you’re making this for a birthday, brunch, or just to satisfy your sweet tooth on a cozy afternoon, you’re going to love it.
We have many sourdough recipes here on the blog! Make sure to browse them as well 🙂
Why You’ll Love This Sourdough Banana Cake
- A soft, fluffy cake, not heavy or dense like banana bread
- Sweetened with ripe bananas and a touch of brown sugar
- A great way to use sourdough discard without any sour taste
- Topped with a whipped brown butter cream cheese frosting that melts in your mouth
- Simple pantry ingredients, minimal fuss, big flavor!
Ingredients
Let’s talk ingredients—because each one plays a role in making this cake soft, flavorful, and moist (but still light!).
For the Banana Cake:
- 3 Overripe Bananas (1 cup mashed): The riper the better! They add natural sweetness and moisture while helping create a tender crumb.
- 1/2 cup Sourdough starter discard: Adds subtle tang and helps keep the cake moist. Bonus points for reducing food waste! Don’t worry—it won’t taste “sour.”
- 2 large eggs: Eggs provide structure and help the cake rise. Room temperature eggs work best for a smooth batter.
- Granulated Sugar (3/4 cup): Gives sweetness and balances the banana flavor.
- 1/4 cup Brown Sugar: Adds warmth and depth. The molasses in brown sugar complements the banana beautifully.
- 1/2 cup Neutral Oil: Keeps the cake super moist without weighing it down. I love using avocado oil, but vegetable or canola work too.
- 1/2 cup Milk: Loosens the batter and adds moisture. Buttermilk also works and adds even more tenderness.
- 1 tsp Vanilla Extract: Enhances all the other flavors.
- 1 3/4 cups All-Purpose Flour: Just the right amount for structure without making the cake dense.
- 1 tsp Baking Powder: These leaveners work together to help the cake rise. The soda reacts with the acidity of the sourdough and bananas.
- 1/2 tsp Baking Soda:
- 1/2 tsp Salt: A little salt brings out the sweetness and balances the flavors.
- 1/2 tsp Cinnamon: Warm spice notes that go beautifully with banana and brown sugar. I always add it.
Instructions
1. Preheat the Oven
Set your oven to 350°F (175°C). Grease and line a 9×13-inch cake pan or two 8-inch round cake pans with parchment paper.
2. Make the Cake Batter
In a large bowl, whisk together mashed bananas, sourdough discard, eggs, white sugar, brown sugar, oil, milk, and vanilla extract until smooth.
In a separate bowl, combine the flour, baking powder, baking soda, salt, and cinnamon. Whisk to distribute evenly.
Add the dry ingredients into the wet ingredients and stir until just combined. Don’t overmix—stop as soon as the flour disappears to keep the crumb light.
3. Bake
Pour the batter into your prepared pan. Bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. Let the cake cool completely before frosting.
Whipped Brown Butter Cream Cheese Frosting
Ingredients:
- 1/2 cup (1 stick) unsalted butter
- 3/4 cup brown sugar
- 2 tbsp heavy cream
- 1/2 tsp salt
- 8 oz cream cheese, softened
- 1/2 cup powdered sugar, sifted
- 1 tsp vanilla extract
Instructions:
- Brown the Butter: In a saucepan, melt the butter over medium heat until it foams and smells nutty, and the solids at the bottom turn golden brown. Don’t walk away, the butter may burn too quickly.
- Make Caramel Base: Add brown sugar, heavy cream, and salt to the browned butter. Simmer gently for 1–2 minutes, or until the sugar has dissolved. Remove from heat.
- Cool It Down: Let this mixture cool to room temperature—it should still be soft but no longer warm.
- Cream the Cheese: Beat the softened cream cheese in a bowl until smooth and fluffy.
- Combine & Whip: Slowly add the cooled brown butter mixture to the cream cheese. Using a hand mixer mix until smooth, then beat in powdered sugar and vanilla until fluffy and well combined.
- Frost the Cake: Once the cake is fully cooled, spread or pipe this luscious frosting over the top. It will set up slightly as it rests.
Storage Tips
- Room Temp: Keep covered on the counter for up to 2 days.
- Fridge: Store in an airtight container for up to 5 days. I love slicing it cold and microwaving a piece for 10 seconds—so good.
- Freezer: You can freeze the unfrosted cake tightly wrapped for up to 2 months. Thaw overnight and frost fresh!
Substitutions & Tips
- No Sourdough Discard? Replace with 1/4 cup flour + 1/4 cup milk.
- Want Extra Tang? Use buttermilk instead of regular milk.
- Dairy-Free? Sub milk with almond or oat milk and use plant-based butter and cream cheese.
- Make It a Layer Cake: Bake in two 8-inch rounds and double the frosting for a bakery-style look.
FAQ
Can I make this into cupcakes?
Yep! It makes about 16–18 cupcakes. Bake at 350°F for 18–20 minutes.
Can I skip the frosting?
Technically yes—but that brown butter cream cheese frosting is what makes this cake shine. If you’re short on time, a dusting of powdered sugar works too.
Can I add nuts or chocolate chips?
Yes! Fold in 1/2 cup of chopped walnuts or chocolate chips before baking for a fun twist.
This sourdough banana cake has become one of my go-to bakes when I need something cozy but not overly sweet. It’s fluffy, flavorful, and that brown butter cream cheese frosting? Chef’s kiss. 💋
If you give this recipe a try, tag me on Instagram @liza_zykin or TikTok @SourdoughQueen. I love seeing your creations!
Sourdough Banana Cake with Brown Butter Frosting
Ingredients
Equipment
Method
- Set your oven to 350°F (175°C). Grease and line a 9×13-inch cake pan or two 8-inch round cake pans with parchment paper.
- In a large bowl, whisk together mashed bananas, sourdough discard, eggs, white sugar, brown sugar, oil, milk, and vanilla extract until smooth.In a separate bowl, combine the flour, baking powder, baking soda, salt, and cinnamon. Whisk to distribute evenly.Add the dry ingredients into the wet ingredients and stir until just combined. Don’t overmix—stop as soon as the flour disappears to keep the crumb light.
- Pour the batter into your prepared pan. Bake for 35–40 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. Let the cake cool completely before frosting.
- Brown the Butter: In a saucepan, melt the butter over medium heat until it foams and smells nutty, and the solids at the bottom turn golden brown. Don’t walk away, the butter may burn too quickly.
- Make Caramel Base: Add brown sugar, heavy cream, and salt to the browned butter. Simmer gently for 1–2 minutes, or until the sugar has dissolved. Remove from heat.
- Cool It Down: Let this mixture cool to room temperature—it should still be soft but no longer warm.
- Cream the Cheese: Beat the softened cream cheese in a bowl until smooth and fluffy.
- Combine & Whip: Slowly add the cooled brown butter mixture to the cream cheese. Using a hand mixer mix until smooth, then beat in powdered sugar and vanilla until fluffy and well combined.
- Frost the Cake: Once the cake is fully cooled, spread or pipe this luscious frosting over the top. It will set up slightly as it rests.
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