This gluten-free sourdough discard banana cake is moist, sweet, and perfectly tender. A simple way to use up extra gluten-free sourdough starter. It's easy to make, tested with multiple gluten-free flour blends, and comes out perfectly every time!
Katie's Recipe Testing Notes!
When testing my gluten-free sourdough discard banana muffin recipe, I ended up with a batch that was a little too light and sweet to be called a muffin-but it made a perfectly delicious cake! So I turned that test into this easy snack cake recipe.
One thing I love about this cake is how easy it is to make. You can mix it up with just a whisk or a hand mixer-no stand mixer or fancy equipment needed.
I tested the recipe with several popular gluten-free flour blends, including a couple of homemade versions, and each one turned out beautifully. The differences in taste and texture were subtle, so you can confidently use your preferred blend. Check out my ingredient notes below for more details on the blends I tested.
Ingredients
- Gluten-Free Flour Blend: I tested this recipe with Bob's Red Mill 1:1, King Arthur Measure for Measure, and Cup4Cup. All three worked well, but I slightly preferred the version with Bob's! You can make it with my Bob's copycat gluten-free flour blend. I even tested a batch with my homemade Cup4Cup blend, and it was great too!
- Sourdough Discard: Adds moisture and a subtle tangy flavor. My sourdough discard is brown rice flour and water.
- Mashed Banana: I found that about 190-200g (¾ cup) works best, which is about 2 small bananas.
- Avocado Oil: Keeps the cake soft. You can swap for melted butter or any vegetable oil.
- Baking Soda & Baking Powder: The balance of each works well with the acidity of the sourdough discard and banana to help the cake rise.
- Cream Cheese Frosting: A simple blend of cream cheese, butter, powdered sugar, vanilla extract, and salt adds a tangy, sweet finish.
*Refer to the recipe card for full ingredient information.
Can I make this dairy-free?
The cake itself is dairy-free! You can use a non-dairy butter and cream cheese for the frosting, or use a store-bought canned frosting, most of which are dairy-free!
How to Make Sourdough Banana Cake
- Step 1: Whisk the dry ingredients together in a small bowl.
- Step 2: In a large mixing bowl, mash the bananas until smooth. Whisk in the sugar, sourdough discard, eggs, oil, and vanilla.
- Step 3: Add the dry ingredients to the wet ingredients and stir just until combined.
- Step 4: Pour the batter into a prepared cake pan and bake 30-35 minutes. Let the cake to cool completely before frosting.
- Step 5: For the frosting, blend together the cream cheese and butter until smooth.
- Step 6: Add the powdered sugar, vanilla extract, and a pinch of salt.
- Step 7: Beat together until light and fluffy.
- Step 8: Spread the frosting over the cooled cake.
Optional Add-Ins & Variations
- Enjoy the cake plain for a simple snack cake.
- Stir chopped walnuts or pecans into the batter.
- Add chocolate chips or chocolate chunks for extra sweetness.
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Storage
The cake stays fresh and moist for 2-3 days when stored in an airtight container at room temperature. It will last a few extra days if refrigerated.
Top Recipe Tips
- Use ripe bananas: The riper, the better! Overripe bananas add natural sweetness and moisture.
- Measure by weight: For the best outcome, measure your ingredients by weight-especially the gluten-free flour and banana!
- Don't overmix the batter: Stir just until combined to keep the cake soft and tender.
- Check for doneness: Since ovens vary, use a toothpick to check for doneness-if it comes out clean, the cake is done! For the most accurate result, a digital thermometer should read 205°F when fully baked.
More Gluten-Free Recipes with Sourdough
If you'd like to see more gluten-free quick bread recipes, I've got those too-like this gluten-free buckwheat banana bread!
Recipe FAQs
I used a brown rice sourdough starter in this recipe, with a 1:1:1 ratio of sourdough, brown rice flour, and water.
Don't have a sourdough starter? Check out my comprehensive guide to gluten-free sourdough starer! I'll walk you through it all step-by-step!
You can make my gluten-free banana bars, instead!
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Recipe
Gluten-Free Sourdough Discard Banana Cake
Ingredients
- 140 g Bob's Red Mill 1:1 Gluten-Free Flour (see notes for other flour blends tested.)
- 1 teaspoon baking powder (5g)
- 1 teaspoon baking soda (5g)
- 1 teaspoon cinnamon (3g)
- ½ teaspoon salt (3g)
- 80 g brown rice sourdough discard
- 195 g mashed banana (about 2 small bananas)
- 176 g granulated sugar
- 40 g avocado oil
- 100 g eggs (2 large)
- 1 teaspoon vanilla extract (6g)
Cream Cheese Frosting
- 113 g cream cheese (softened)
- 57 g unsalted butter (softened)
- 240 g powdered sugar
- ½ teaspoon vanilla extract
- Pinch of salt
Instructions
- Preheat the oven to 350°F. Grease and line an 8x8-inch square pan with parchment paper.
- In a small bowl, whisk together the gluten-free flour, baking powder, baking soda, cinnamon, and salt.
- In a large mixing bowl, mash the bananas until smooth. Whisk in sourdough discard, sugar, eggs, oil, and vanilla until combined.
- Add the dry ingredients to the wet and stir until just combined. Do not overmix.
- Pour the batter into the prepared pan and spread evenly.
- Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean and a digital thermometer reads 205°F.
- Let cool in the pan for 10 minutes, then transfer to a wire cooling rack to cool completely.
Cream Cheese Frosting
- In a medium bowl, beat together the cream cheese and butter until smooth and creamy.
- Add the powdered sugar, vanilla, and salt. Beat until light and fluffy.
- Spread the frosting over the cooled cake.
Notes
Nutrition
* Nutritional information is provided as a courtesy and should be used as an estimate only. See the nutrition policy for more information.
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