- 12 tablespoons unsalted butter at room temperature
- 1 1/2 cups granulated sugar
- 3 extra-large eggs at room temperature
- 1 1/2 teaspoons pure vanilla extract
- 2 tablespoons of instant coffee powder
- 1 1/4 cups sour cream
- 2 1/2 cups cake flour
- 2 teaspoons baking powder
- 1/2 teaspoon baking soda
- 1/2 teaspoon kosher salt
For the streusel:
- 1/4 cup light brown sugar
- 1/2 cup all-purpose flour
- 1 1/2 teaspoons ground cinnamon
- 1/4 teaspoon salt
- 3 tablespoons cold unsalted butter, cut into pieces
- 3/4 cup chopped walnuts, optional
- Preheat the oven to 350 degrees F. Grease and flour a pan.
- Cream the butter and sugar in the bowl for 4 to 5 minutes, until light. Add the eggs 1 at a time, then add the vanilla and sour cream. In a separate bowl, sift together the flour, baking powder, baking soda, coffee powder and salt. With the mixer on low, add the flour mixture to the batter until combined.
- For the streusel, place the brown sugar, flour, cinnamon, salt, and butter in a bowl and pinch together with your fingers until it forms a crumble. Mix in the walnuts, if desired.
- Spoon half the batter into the pan and spread it out with a knife. Sprinkle with 3/4 cup streusel. Spoon the rest of the batter in the pan, spread it out, and scatter the remaining streusel on top. Bake for 50 to 60 minutes, until a cake tester comes out clean.