Ingredients
Scale
For the Cake:
- 1 cup active sourdough starter (fed and bubbly)
- 1½ cups all-purpose flour
- ¾ cup granulated sugar
- ½ cup unsalted butter, softened
- ½ cup sour cream
- 2 large eggs
- 1 teaspoon baking powder
- ½ teaspoon baking soda
- ½ teaspoon salt
- 1 teaspoon vanilla extract
- ⅓ cup milk
For the Cinnamon Streusel:
- ¾ cup brown sugar, packed
- ½ cup all-purpose flour
- ½ cup cold unsalted butter, cubed
- 2 teaspoons ground cinnamon
- ½ cup chopped walnuts (optional)
Instructions
- Prepare Your Workspace – Preheat oven to 350°F. Grease 9×9-inch pan and line with parchment paper for easy removal.
- Create Perfect Streusel – Mix brown sugar, flour, and cinnamon. Cut in cold butter until crumbly with pea-sized pieces. Keep refrigerated.
- Master the Dry Mix – Whisk flour, baking powder, baking soda, and salt until evenly distributed. Sift if lumpy.
- Achieve Bakery Texture – Cream butter and sugar 4-5 minutes until light and fluffy for tender results.
- Build Sourdough Foundation – Beat in eggs one at a time, then active sourdough starter, sour cream, and vanilla for incredible tang.
- Critical Combining – Alternate flour mixture with milk, mixing just until combined. Don’t overmix.
- Layer Like a Pro – Spread half batter, add half streusel, remaining batter, then final streusel layer.
- Bake to Perfection – Bake 45-55 minutes until toothpick shows moist crumbs.
- Cool for Best Results – Cool 15 minutes before removing for clean slicing.
Notes
- Perfect your sourdough starter timing – use when active and bubbly, ideally 4-8 hours after feeding. Wait for it to double in size with surface bubbles.
- Keep streusel cold – chill 10-15 minutes if your kitchen is warm to prevent melting during baking.
- Room temperature ingredients mix easier and create better texture. Take eggs, sour cream, and butter out 1-2 hours early.
- Layer like a pro – half batter, half streusel, remaining batter, final streusel for gorgeous swirls.
Master doneness – toothpick should show just a few moist crumbs, not completely clean. - Don’t overmix once flour is added. Fold gently since sourdough starter has already developed gluten.
- Store properly – cover tightly. Actually improves after day one as flavors meld, staying moist up to one week.