This spice cake is filled with bold flavor from warm Fall baking spices and is topped with a buttery cinnamon streusel. With all this flavor, no one will notice there's sourdough starter discard in it!
[Side Note: a version of this post first appeared on my OutlanderCast column, October 9, 2018]
Why this recipe works
- Spice cake is boldly flavored with warm baking spices
- Using unfed sourdough starter in the batter is a great way to use starter discard, and you won't know it's there
- A buttery streusel topping adds even more goodness to this cake
Autumn is a season of transitions.
The heat of summer cools to the eventual cold of winter. Here in New England the trees put on a show of color the likes of which I still marvel at, California girl that I am. Kids go back to school, or some head there for the first time. And pumpkin spice lattes start popping up at your local coffee shops.
I love all the Fall flavors, from Pumpkin Bread to Glazed Orange-Cranberry Bread, both being two examples of quick bread recipes. I also enjoy a soft and flavorful Spice Cake.
Longtime readers know that I’m always looking for sourdough discard recipes for my weekly unfed sourdough starter (that's what you remove from your starter container when you feed it). Hold on to your spatulas...here comes my recipe for Sourdough Spice Cake!
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What you need
The basic ingredients for this spice cake recipe include flour, water, eggs, sugar, canola oil, baking soda, vanilla extract, and salt. Sour cream adds moisture, and the cake is flavored with the warm baking spices of cinnamon, ginger, nutmeg, and cloves. And then there's the sourdough starter discard.
(Sourdough in a cake? Really?)
Don’t worry that the cake has sourdough starter discard in it. The spices take the spotlight unto themselves and cover any sourdough tanginess. Including the unfed starter is just a way of using up the discard instead of throwing it away. Honestly, you won’t taste it.

The topping consists of butter, sugar and brown sugar, flour, cinnamon, and salt. Adding the streusel topping brings a buttery crunch to the top of the cake. It's not unlike the topping found on my Apple Crisp recipe (aka Apple Crumble), minus the oats.

How to make a Sourdough Spice Cake
Since this recipe for Sourdough Spice Cake is a quick bread, it comes together...uhm...quickly.
Step 1: Make the streusel topping
The method for making streusel is very similar to making biscuits or scones in that you start with a flour mixture, then add butter to until you get something resembling pea-sized crumbs.
Whisk the flour, both sugars, cinnamon, and salt in a small bowl (photo 1).

Cut in the cold butter using a fork or your hands until the mixture resembles pea-sized crumbs (photo 2).

Place the streusel in the refrigerator while you make the batter (photo 3). It's important to keep the streusel chilled - that keeps it from melting into the batter when the cake is baking. I learned that the hard way, as you can tell from the pictures.

Step 2: Make the batter
In a large mixing bowl, whisk together flour, sugar, brown sugar, baking soda, salt, and spices. If necessary, mash any large lumps of brown sugar (photo 4).

Add the sourdough starter, egg, sour cream, oil, and vanilla to the flour mixture. Stir together until everything is just combined (photo 5).

Step 3: Bake the spice cake
Pour the batter into a standard loaf pan that's been sprayed with baking spray and lined with parchment paper. Top the batter evenly with the streusel, pressing it down gently into the top of the bread so it sticks.
Bake at 350˚F for 45 to 55 minutes, or until a toothpick inserted in the center comes out clean (photo 6).

Questions asked and answered
Here are some questions you might have...
Unlike yeast-leavened bread, quick breads are leavened with baking soda or baking powder and require a little stirring rather than a heavy kneading. They're in the same category as tea cakes (like Orange Cranberry Bread), and can be baked in a loaf pan (standard size or mini), individual muffins (again full-sized or mini), or in a bundt pan.
Quick bread batter is closer in texture to cake batter than bread dough, but quick breads are generally denser than cakes. Also, they don't have to be sweet. An example of a savory quick bread is cornbread.
Using unfed sourdough in sweet baked goods is a great use as generally the taste is covered by other strongly flavored ingredients, like in this Sourdough Gingerbread recipe.
If you really don't want to use sourdough starter in this cake (or don't have any discard handy), then you can substitute a scant cup of flour (4 ounces, 114 grams) and ½ cup of warm water (4 ounces, 118 grams) for the 1 cup of unfed sourdough starter and increase the salt to 1 teaspoon.

Pro Tip: Other ways to serve this cake
One of the benefits of baking quick breads is that they can be baked in different sizes and shapes. You're not limited to a standard loaf. Here are some suggestions for alternative presentations:
- One large loaf in a standard loaf pan plus two mini loaves using mini loaf pans. Bake the large loaf for 35 to 40 minutes and the mini loaves for 25 to 30 minutes
- Six mini loaves using mini loaf pans. Bake for for 25 to 30 minutes
- Twelve full-size muffins in a standard muffin pan, each well filled ⅔ full. Bake for 18 to 23 minutes
- One small bundt cake in a 6-cup bundt pan. Bake for 35 to 45 minutes
And don't forget that quick breads as mini bundts or loaves make great gifts and ship well!
A spice cake like no other
Sourdough Spice Cake with its cinnamon streusel topping is so flavorful! This sweet bread is loaded with spicy fall flavors, and is moist and soft. The spicy flavors overpower any tanginess from the sourdough starter discard. The streusel topping adds a delicious buttery crunch that provides a texture contrast to the cake.
This cake should stay fresh at room temperature for up to 3 days or in the refrigerator for up to a week. For longer storage, you can freeze it for up to 3 months. Allow it to thaw overnight in the refrigerator and bring to room temperature before serving.

Whether you serve this cake for brunch, dessert, or for an afternoon snack on a chilly Autumn day, you're in for a treat.
Move over, Pumpkin Spice, this streusel-topped Sourdough Spice Cake is in the house!
Slainté! L’chaim! Cheers!
Tammy
Related Recipes
When you maintain a sourdough starter, you have a dilemma. What do you do with your unfed sourdough starter discard? I've got lots of suggestions for sweet and savory ways to use your fed sourdough starter and the sourdough starter discard.
Good news for sourdough bakers! I've published an e-book that allows you to discover a new method to feed your starter with less flour, making your baking both sustainable and scrumptious. Learn how to have the right amount of starter for your favorite sourdough bread recipe, and explore various bread baking pans to level up your baking game. Plus, dive into a bonus recipe for a naturally-leavened sourdough bread using unfed starter that will fit into your busy schedule for fresh bread any time. Head over to my shop and get your copy today!
And if you sign up to receive my weekly featured recipe email, I'll send you the recipe for Extra-Tangy Sourdough Bread. Enjoy!
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Recipe

Cinnamon Streusel Sourdough Spice Cake
Ingredients
For the streusel topping
- ¼ cup all-purpose flour
- 1 tablespoon granulated sugar
- 1 tablespoon dark brown sugar, packed
- ½ teaspoon ground cinnamon
- ¼ teaspoon kosher salt
- 4 tablespoons unsalted butter, cold, cubed
For the batter
- 1½ cups all-purpose flour
- ½ cup granulated sugar
- ½ cup brown sugar
- 2 teaspoons baking soda
- ½ teaspoon kosher salt
- 1 teaspoon ground cinnamon
- ½ teaspoon ground cloves
- ¼ teaspoon ground ginger
- ⅛ teaspoon ground nutmeg
- 1 cup sourdough starter discard, at room temperature, see Recipe Notes
- 1 large egg, at room temperature
- ½ cup sour cream, or plain yogurt (regular or Greek), at room temperature
- ¼ cup canola oil, see Recipe Notes
- 1 teaspoon pure vanilla extract
Instructions
- Preheat oven to 350 °F. Spray a standard loaf pan with baking spray, and line with parchment paper leaving a 2-inch overhang on the long sides.
- Prepare the streusel: Whisk the flour, both sugars, cinnamon, and salt in a small bowl. Cut in the cold butter using a fork or your hands until the mixture resembles pea-sized crumbs. Place the streusel in the refrigerator while you make the batter. It's important to keep the streusel chilled - that keeps it from melting into the batter when the cake is baking.
- Prepare the batter: In a large mixing bowl, whisk together flour, sugar, brown sugar, baking soda, salt, and spices. If necessary, mash any large lumps of brown sugar.
- Add the sourdough starter, egg, sour cream, canola oil, and vanilla to the flour mixture. Stir together until everything is just combined.
- Pour the batter into prepared loaf pan. Top the batter evenly with the streusel, pressing it down gently into the top of the bread so it sticks.
- Bake for 45 to 55 minutes, or until a cake tester inserted in the center comes out clean.
- Cool the bread in the pan on a wire rack for about 15 minutes, then remove it from the pan using the parchment paper as a sling and allow it to cool completely. Serve & enjoy!
- Storage instructions: Sourdough Spice Cake should stay fresh at room temperature for up to 3 days or in the refrigerator for up to a week. For longer storage, you can freeze it for up to 3 months. Allow it to thaw overnight in the refrigerator and bring to room temperature before serving. This cake also makes a great gift and ships well!
Notes
- One large loaf in a standard loaf pan plus two mini loaves using mini loaf pans. Bake the large loaf for 35 to 40 minutes and the mini loaves for 25 to 30 minutes
- Six mini loaves using mini loaf pans. Bake for for 25 to 30 minutes
- Twelve full-size muffins in a standard muffin pan, each well filled ⅔ full. Bake for 18 to 23 minutes
- One small bundt cake in a 6-cup bundt pan. Bake for 35 to 45 minutes
Christine says
Hello Tammy,
This sourdough spice cake sounds delicious. My sourdough culture is about one week from being ready to use and I would like to try it in your recipe. I notice that you suggest 2 teaspoons of baking soda for this recipe and was wondering if you could confirm this is the correct quantity as it seems to me to be quite a lot of baking soda to use.
Regards, Christine
Tammy Spencer says
Hi Christine, thanks for your question. Yes, the recipe does call for 2 teaspoons of baking soda. The sour cream reacts with the baking soda, so there isn't a metallic aftertaste (at least not one that I notice). My Sourdough Banana Bread is a variation of this recipe, and the same is true there. I haven't tested either recipe with less baking soda, but that might be an interesting experiment. If you do decide to use less, please let me know how it goes. Welcome to the world of sourdough, and happy baking! 😉