Sourdough Discard Carrot Cake Recipe for Moist, Flavorful Loaf

1. Step 1: Whisk dry ingredients together (except sugars).

2. Step 2: Shred carrots using the small holes of a box grater.

3. Step 3: Mix sugars, oil, eggs, and vanilla until smooth, then add sourdough discard.

4. Step 4: Fold dry ingredients into wet until just combined.

5. Step 5: Fold in carrots, walnuts, and raisins.

6. Step 6: Pour batter into the prepared pan and bake until a toothpick comes out clean.

7. Step 7: Once the cake is fully cooled, whip the frosting ingredients until smooth.

8. Step 8: Spread frosting, slice, and serve.

Sourdough discard is the portion of starter removed when you feed your starter. Rather than throwing it away, you can use it in baked goods like this carrot cake to add flavor and reduce waste.

Yes. While not specifically tested by the author, bake times will be shorter—start checking at 12 minutes and expect up to about 20 minutes depending on your oven and muffin size.

A 9-inch round pan has less area than a 9×9 square, so the batter will be deeper. You can bake in a 9-inch round, but expect longer bake time and consider tenting with foil toward the end to prevent over-browning. Alternatively, reduce quantities by roughly 20% to better match pan size.

Yes. Replace the sour cream in the frosting with an equal amount of cream cheese. Note that some dairy-free cream cheeses may not produce the same texture or flavor as dairy cream cheese; the sour cream frosting is a reliable dairy-free option.

No. Use dairy or dairy-free sour cream based on preference or dietary needs. Both work well in the frosting.

For the Cake:

• ¾ cup all-purpose flour
• 1 ½ teaspoons baking soda
• 1 ½ teaspoons baking powder
• 1 ½ teaspoons ground cinnamon
• 1 teaspoon ground ginger
• ½ teaspoon ground cloves
• ½ teaspoon ground nutmeg
• ¼ teaspoon kosher salt
• ⅔ cup packed brown sugar
• ⅔ cup granulated sugar
• ⅓ cup vegetable oil
• 2 eggs
• 1 ½ teaspoons vanilla extract
• 200 grams (about ¾ cup) sourdough discard, unfed and at room temperature
• 2 cups shredded carrots
• ½ cup chopped walnuts (optional)
• ¼ cup raisins (optional)

For the Frosting:

• 4 Tablespoons unsalted butter, softened
• 4 Tablespoons sour cream (dairy or non-dairy), at room temperature
• ½ teaspoon vanilla extract
• 1 ¾ cups confectioner’s sugar

1. Preheat oven to 350℉. Grease and flour a 9×9-inch pan (or line with parchment) and set aside.
2. In a small bowl, whisk flour, baking soda, baking powder, cinnamon, ginger, cloves, nutmeg, and salt. Set aside.
3. Peel and shred carrots on the small holes of a box grater. Set aside.
4. In a large bowl, use a hand mixer to beat the brown sugar, granulated sugar, oil, eggs, and vanilla until smooth and slightly fluffy, about 1 minute. Add the sourdough discard and mix until smooth.
5. Fold the dry ingredients into the wet mixture until just combined and no dry spots remain. Fold in shredded carrots, walnuts, and raisins. Transfer batter to the prepared pan.
6. Bake 45–50 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan 15 minutes, then transfer to a cooling rack to cool completely.
7. For the frosting: Beat softened butter until creamy (2–3 minutes). Add sour cream and vanilla and mix until smooth. Add confectioner’s sugar and beat until combined. If the frosting is too thick, add sour cream 1 tablespoon at a time until you reach your desired consistency.
8. When the cake is fully cooled, spread the frosting over the cake. Slice and serve.

*If you prefer not to grease and flour the pan, you can line it with parchment paper after greasing for easy removal.

To make a cream cheese frosting: Use 4 Tbsp cream cheese in place of the sour cream and follow the same steps. Note that some dairy-free cream cheeses may yield different texture or flavor; sour cream is a reliable non-dairy option.

To bake with active starter: Substitute 200g active starter for the discard without other changes.