Moist Spiced Sourdough Banana Cake Recipe for Tangy Flavor

This sourdough banana cake uses starter discard and a jelly roll pan for quick baking and an extra-soft crumb. It’s lightly spiced with cinnamon and comes together fast—no creaming butter and no long loaf-bake. A thrifty sourdough-discard recipe perfect for using up ripe bananas.

Ingredients and Tools You’ll Need

Just pantry staples and a couple of very ripe bananas. A 10×15-inch jelly roll pan gives fast, even baking and a great cake-to-frosting ratio.

For the Cake

• 2 very ripe bananas, mashed
• ½ cup granulated sugar
• ½ cup brown sugar
• ½ cup vegetable oil
• 2 eggs
• 1 teaspoon vanilla extract
• 2 cups all-purpose flour
• 1 teaspoon baking soda
• 1 teaspoon baking powder
• ½ teaspoon salt
• 2 teaspoons ground cinnamon
• ½ cup sourdough starter discard (unfed is fine)

For the Frosting

• 4 ounces cream cheese, room temperature
• 6 tablespoons butter, room temperature
• 1 teaspoon vanilla extract
• 2½ cups powdered sugar (sift if lumpy)

How to Make Sourdough Banana Cake

This is straightforward and quick.

Step 1: Mash the bananas and mix the wet ingredients

In a large bowl, mash two very ripe bananas. Add the granulated sugar, brown sugar, and vegetable oil. Beat with a hand mixer or whisk until fairly smooth—small banana bits are fine. Add the eggs and vanilla and mix until combined.

Step 2: Add the dry ingredients

Sprinkle the flour, baking soda, baking powder, salt, and cinnamon directly into the wet mixture—no separate bowl needed. Start the mixer on low so flour doesn’t puff, and mix just until the flour disappears. Avoid overmixing.

Step 3: Stir in the sourdough discard

Add the sourdough discard (unfed) and fold it in by hand with a spatula or wooden spoon to keep the batter tender.

Step 4: Spread the batter into the jelly roll pan

Grease a 10×15-inch jelly roll pan with nonstick spray or shortening and dust lightly with flour. Pour in the batter and smooth the top evenly. Because the pan is shallow, the cake bakes quickly and stays soft.

Step 5: Bake until golden and springy

Bake at 350°F for about 17–20 minutes. Begin checking at 17 minutes: the cake is done when the top springs back lightly and a toothpick inserted in the center comes out clean. Let the cake cool completely in the pan before frosting.

Step 6: Make the frosting

Beat room-temperature cream cheese and butter until smooth. Add the vanilla, then add powdered sugar in two additions, mixing on low then finishing on medium until creamy and spreadable. Cold ingredients can make the frosting lumpy, so bring them to room temperature first.

Step 7: Frost and serve

Spread the frosting over the cooled cake, smoothing to the edges. Cut into neat squares—ideal for serving a crowd.

Storage and Make-Ahead Tips

Store the cake tightly covered in the refrigerator for up to 5 days. For best texture, let slices sit at room temperature 15–20 minutes before serving. You can also bake the cake a day ahead and frost just before serving.

Printable Recipe

Sourdough Banana Cake

Moist, spiced, and finished with cream cheese frosting, this sourdough banana cake makes good use of starter discard and bakes in under 20 minutes in a jelly roll pan.

Prep Time: 15 mins

Cook Time: 20 mins

Cooling time: 1 hr

Total Time: 35 mins

Servings: 15 slices

Ingredients

For the Cake

• 2 very ripe bananas, mashed
• ½ cup granulated sugar
• ½ cup brown sugar
• ½ cup vegetable oil
• 2 eggs
• 1 teaspoon vanilla extract
• 2 cups all-purpose flour
• 1 teaspoon baking soda
• 1 teaspoon baking powder
• ½ teaspoon salt
• 2 teaspoons ground cinnamon
• ½ cup sourdough starter discard (unfed)

For the Frosting

• 4 ounces cream cheese, room temperature
• 6 tablespoons butter, room temperature
• 1 teaspoon vanilla extract
• 2½ cups powdered sugar

Instructions

The cake

1. Preheat oven to 350°F. Grease a 10×15-inch jelly roll pan with baking spray or shortening and dust lightly with flour.
2. In a large bowl, beat mashed bananas, granulated sugar, brown sugar, and oil until fairly smooth. Add eggs and vanilla and mix until combined.
3. Add the flour, baking soda, baking powder, salt, and cinnamon directly to the bowl. Mix on low until just combined, then stir in the sourdough discard by hand.
4. Pour batter into the prepared pan and smooth the top. Bake 17–20 minutes, until the top springs back and a toothpick comes out clean. Cool completely in the pan.

The frosting

1. Beat cream cheese and butter until smooth. Add vanilla. Add powdered sugar in two batches, mixing on low then beating until creamy.
2. Spread frosting over the cooled cake and cut into squares to serve.

Notes

This cake also works in a 9-inch square or round pan—bake 45–50 minutes. If you prefer not to use cream cheese frosting, a caramel glaze or a dusting of powdered sugar are good alternatives. Store covered in the fridge up to 5 days.

Nutrition (per slice)

Calories: 355 kcal • Carbs: 53 g • Protein: 3 g • Fat: 15 g • Sugar: 36 g