Carrot Cake with Sourdough Discard

Moist, warmly spiced, and topped with cream cheese frosting — an old-fashioned favorite made better with sourdough.

At a Glance

• Loaf Style: Single-layer cake

• Skill Level: Beginner-friendly

• Total Time: ~12–18 hours (includes optional chill)

• Prep Time: ~30 minutes

• Yield: One 8x8” square or one 9” round cake

• Hydration: N/A

• Bake Temp: 350°F / 175°C

• Baking Vessel: Square or round cake pan

Ingredients

Cake

• 100g sourdough discard (unfed starter)

• 200g grated carrot (about 2 medium carrots)

• 120g all-purpose flour

• 100g brown sugar

• 50g granulated sugar

• 2 large eggs

• 120g neutral oil (e.g. sunflower, grapeseed, or light olive oil)

• 1 tsp vanilla extract

• 1 tsp ground cinnamon

• ½ tsp ground ginger

• ¼ tsp ground nutmeg

• ½ tsp baking powder

• ½ tsp baking soda

• ¼ tsp salt

• Optional: 50g chopped walnuts or pecans, 50g raisins or crushed pineapple

Cream Cheese Frosting

• 100g cream cheese, softened

• 50g unsalted butter, softened

• 100g powdered sugar

• ½ tsp vanilla extract

• Pinch of salt

Instructions

Make the Batter
1. In a large mixing bowl, whisk together oil, sugars, eggs, vanilla, and sourdough discard until smooth.
2. Stir in the grated carrots.
3. In a separate bowl, whisk together flour, spices, baking powder, baking soda, and salt.
4. Add dry ingredients to the wet mixture and fold gently until just combined.
5. Fold in optional add-ins like nuts, raisins, or pineapple if using.

Rest (Optional for Better Flavor)
6. For enhanced moisture and sourdough complexity, cover and refrigerate the batter for 8–12 hours.
7. If baking right away, proceed to the next step.

Bake
8. Preheat oven to 350°F / 175°C. Grease and line an 8x8” or 9” round cake pan.
9. Pour in the batter and smooth the top.
10. Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean.
11. Cool in the pan for 10 minutes, then turn out onto a rack and cool completely before frosting.

Make the Frosting
12. In a mixing bowl, beat cream cheese and butter until smooth.
13. Add powdered sugar, vanilla, and salt. Beat until fluffy and spreadable.
14. Frost the cooled cake and garnish with extra nuts or a light dusting of cinnamon if desired.

Visual Cues

• Cake should be softly domed with a moist crumb and golden-brown edges.

• Once frosted, it should look plush and inviting, with visible flecks of carrot throughout.

Why This Works

Sourdough discard adds structure and depth of flavor without interfering with the cake’s classic warmth. The result is a more nuanced, tender carrot cake — gently tangy, beautifully moist, and timelessly comforting.