Sourdough Marble Cake
Buttery and soft with dramatic chocolate swirls — a striking, two-tone loaf elevated with sourdough complexity.
At a Glance
Loaf Style: Swirled quick bread
Skill Level: Intermediate
Total Time: ~12–18 hours (includes optional chill)
Prep Time: ~30 minutes
Yield: One loaf (9x5” tin)
Hydration: N/A
Bake Temp: 350°F / 175°C
Baking Vessel: Loaf tin lined with parchment
Ingredients
Base Batter
100g sourdough starter (active or discard)
180g all-purpose flour
½ tsp salt
1 tsp baking powder
¼ tsp baking soda
115g unsalted butter, softened
100g granulated sugar
2 large eggs
100g whole milk or plain yogurt
1 tsp vanilla extract
Chocolate Swirl
15g cocoa powder
15g sugar
1 tbsp milk
Instructions
Cream Butter & Sugar
1. In a large mixing bowl, beat the butter and sugar together until pale and fluffy.
2. Add eggs one at a time, then stir in the sourdough starter, milk, and vanilla until smooth.
Add Dry Ingredients
3. In a separate bowl, whisk together flour, salt, baking powder, and baking soda.
4. Fold dry ingredients into the wet mixture until just combined.
Divide and Flavor
5. Scoop out one-third of the batter into a small bowl.
6. Stir in cocoa powder, sugar, and 1 tbsp milk to make the chocolate swirl batter.
Assemble the Marble Swirl
7. Spoon alternating dollops of vanilla and chocolate batter into a greased and lined loaf tin.
8. Use a skewer or knife to gently swirl the batters together in a figure-eight motion — don’t overmix.
Rest (Optional but Recommended)
9. For deeper flavor and a more cohesive crumb, cover and refrigerate the batter in the tin for 8–12 hours.
10. If baking immediately, proceed to next step.
Bake
11. Preheat oven to 350°F / 175°C.
12. Bake for 50–60 minutes, or until a skewer inserted into the center comes out clean.
13. Cool in the tin for 10 minutes, then lift out and cool completely on a wire rack.
Visual Cues
The loaf should rise with a gentle dome and distinct marbled pattern visible on the top and inside.
Crumb should be fine, moist, and soft with ribbons of cocoa threading through vanilla.
Why This Works
Sourdough discard lends tenderness, structure, and a subtle depth of flavor to this classic loaf. The cocoa swirl balances the vanilla richness, creating a cake that’s not too sweet — just delightfully refined, slice after slice.
