Coffee Cake
Filling:
| ¾ | cup brown sugar |
| ¼ | cup flour |
| 2 | teaspoons ground cinnamon |
Streusel Topping:
| ⅔ | cup brown sugar |
| 1 | cup flour |
| 2 | teaspoons ground cinnamon |
| ¼ | teaspoon salt |
| ½ | cup unsalted butter |
Cake:
| ¾ | cup unsalted butter |
| 1 | cup white sugar |
| ½ | cup brown sugar |
| 3 | eggs |
| 2 | teaspoons vanilla extract |
| 1 | cup sour cream |
| 2¼ | cups flour |
| ¼ | cup cornstarch |
| 2½ | teaspoons baking powder |
| ¾ | teaspoon salt |
Grease 9×9‑inch square pan. Pre-heat oven to 350° F, setting rack toward the center. Whisk together filling ingredients in a small bowl. Set aside. In another bowl, whisk together dry streusel ingredients. Cube butter and cut into the dry ingredients with pastry cutter or by hand until crumbly. Set aside.
For the cake batter, beat butter and white sugar together until light and fluffy, then mix in the brown sugar. Pour in vanilla. While mixing on low, add one egg at a time. Add sour cream and mix until combined. Sift together the flour, cornstarch, baking powder, and salt. Slowly add to the wet ingredients, and beat until just combined.
Pour half the batter into the prepared pan. Sprinkle the filling mixture over top. Spread the remaining batter on top of the filling. Top with the streusel mixture. Bake for about 50 to 55 minutes until a toothpick comes out clean. Allow to cool about 20 minutes before removing from pan.