Sourdough Vanilla Cake

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This simple sourdough vanilla cake is a great way to use some sourdough starter discard. It’s soft and lightly sweet and comes together quickly. Double the recipe to make a 9″x13″ and feed a crowd.

If you, like me, tend to overfeed your sourdough starter, you probably have a jar of discard living in your fridge. Heaven forbid it be thrown away, but goodness, it’s a lot of spent starter.

Enter all the creative ways to use said starter discard. While I have a whole list of ideas (click here to see it), this sourdough vanilla cake might just be the best option yet.

It’s perfect for a birthday cake, and can easily be doubled to serve a crowd. Or, it’s simple enough to whip up to just satisfy a craving. It can be frosted simply or decorated more elaborately. I’m using a recipe for boiled chocolate frosting to top this cake, but you can use whatever you’d like!

Ingredients

For the Cake:

Sourdough Starter Discard
Milk
Eggs
Oil
Vanilla
Sugar
Flour
Salt
Baking Powder
Baking Soda

For the Boiled Chocolate Icing:

Milk
Granulated Sugar
Cocoa Powder
Butter

Prepping the Cake Pan

Using an 8″ or 9″ square pan, cut two sections of parchment paper to the width of the pan. Place the pieces of parchment in the pan in opposite directions, press them into the corners of the pan, and secure in place with metal binder clips. Grease the parchment paper lightly.

Alternatively, you can grease and flour a pan well, but this works best if you plan to leave it in the pan for cutting and serving.

Mixing the Cake Batter

Preheat the oven to 350°, with a rack placed in the center.

In a large mixing bowl, whisk the sourdough starter and milk together. Stir in the sugar, then the egg, egg yolk, and vanilla. You should have a smooth, cohesive mixture that is somewhat thick.

All of the wet ingredients, whisked together until smooth.

Place a sieve over a separate bowl, and sift the flour, salt, baking powder, and baking soda through it. Stir to distribute the rising agents.

Move the sieve over the bowl holding the wet ingredients. Sift the dry ingredients through the sieve again into the wet, then stir it just until they are combined and no more flour is visible.

Sifting the dry ingredients into the wet.

Pour the sourdough cake batter into the prepared pan and smooth it into an even layer. Place it in the oven on the center rack. Bake it for 25-28 minutes, or until the center of the cake is set and the edges are golden brown.

Pouring the batter into the parchment-lined cake pan.

The sourdough cake after baking, with a light golden brown color on the top.

Remove the cake from the oven and allow it to cool before frosting and decorating.

Decorating and Frosting the Cake

For this Cake, I used this vintage recipe for chocolate boiled icing. It’s thick and fudgy and pairs perfectly with the vanilla sponge. However, you can top the cake with whatever you’d like! Some great options are brown butter frosting, chocolate fudge frosting, or fresh strawberry buttercream.

Pouring cooked chocolate frosting over the sourdough vanilla cake.

If you wish to add sprinkles on top, be sure to do it before the frosting has hardened. If not, they won’t stick to the cake and will all fall off when you cut and plate it.

Recipe Tips, Notes, and FAQs

I know the double flour sifting feels like…a lot. But it really helps distribute the rising agents in the flour, and by extension, the cake. It also helps prevent a tough, chewy crumb.
If you want to double the recipe to make a 9″x13″ cake, you can use 3 whole eggs instead of 2 eggs and 2 egg yolks.

Can I use active sourdough starter to make vanilla cake?

Yes, you can! In fact, you can see a few bubbles in the starter I’m using in the photos. However, I prefer using a completely flat starter, as it gives you a more tender crumb.

Can I use butter instead of oil in cakes?

Yes, you absolutely can! However, because of the water content in butter (which evaporates during baking), it can make your cake stale and dry more quickly. Also, since it’s a fat that’s solid when cold, your cake should be at room temperature before eating or the butter will give it a dry mouthfeel.