Sour Cream Streusel Coffee Cake Cake: 1 1/2 cups Biscuit & Baking Mix (Bisquick, or Generic) 1/2 cup sugar 1 egg 3/4 cup sour cream 1/2 teaspoon vanilla Topping: 1/2 cup packed golden brown sugar 1/2 cup all purpose flour 3 tablespoons butter, softened 2 teaspoons vanilla extract just a bit of powdered sugar for sprinkling Preheat oven to 350 degrees. For the cake, stir all of the ingredients together in a large mixing bowl until thoroughly mixed. Spread batter into a greased 8-inch square pan. For the topping, mix all topping ingredients together in a medium-sized bowl, until crumbly. Sprinkle topping over the top of the cake batter. Bake for 30 minutes or until a toothpick inserted into the center of the cake comes out clean. Once the cake has cooled, powder the top of the cake with the powdered sugar so it makes a nice contrast with the brown sugar topping.