Prepare the Oven & Pan:
Preheat oven to 175°C (350°F). Grease and flour a 9-inch round or square pan (or use a springform pan).
Make the Coffee Streusel:
In a small bowl, mix brown sugar, flour, espresso powder, and cinnamon. Cut in the cold butter until coarse crumbs form. Set aside.
Prepare the Cake Batter:
Cream butter and granulated sugar until light and fluffy. Add eggs one at a time, mixing well after each, then stir in vanilla. Mix in sour cream and cooled coffee.
In a separate bowl, whisk flour, baking powder, baking soda, and salt. Gradually fold into the wet ingredients until just combined.
Assemble the Cake:
Pour half the batter into the pan and smooth. Sprinkle half the streusel over it. Repeat with remaining batter and streusel.
Bake:
Bake for 40-45 minutes or until a toothpick inserted comes out clean. Let cool for 15 minutes.
Prepare the Glaze:
Whisk powdered sugar, espresso, and vanilla until smooth. Drizzle over the warm cake.
Serving and Storage Tips
