This is a favorite of my oldest daughter. It takes some attention, but is probably the most perfect coffee cake I’ve ever eaten.

You’ll need a tube pan like you use for angel food cake.  If the bottom is removable, wrap the pan in aluminum foil before you start or the batter will leak out.  Butter the pan well with 2 tablespoons of butter. Set up the oven by taking out all but one rack and putting that one rack near the bottom of the oven so the pan will fit.  Preheat to 350 degrees.

Streusel Topping

Mix together 3/4 cup unbleached all purpose flour, 1/4  cup granulated sugar, 1/4 cup packed dark brown sugar, and 2 tablespoons ground cinnamon.

Put 1 1/4 cups of this mixture aside into a small bowl and stir 1/4 cups of brown sugar into this set aside mixture.  This will be the streusel for the inside the cake. Mix the rest of the topping with 2 tablespoons cold butter (some would add nuts, but we never do) and set aside. This will be streusel for the top of the cake. 

Cake:

Combine 4 large eggs, 1 tablespoon vanilla and 1 cup sour cream in a bowl. Sift 2 1/4 cup flour, 1 1/4 cup granulated sugar, 1 tablespoon baking powder,1/4 tablespoon baking soda and 1/4 tablespoon salt  into another bowl and add 1/2 cup sour cream and 3/4 cup softened butter, mix until dry ingredients are moistened. Then beat well, scraping sides of bowl. Add the egg mixture in three steps, beating after each. Beat well again until you see batter begin to become puffy and increase in size.

Now you’re ready to assemble the cake. Start filling the prepared tube pan with 3 cups of batter, follow with 3/4 cups of the streusel for the interior, one cup of batter, and then the remaining interior streusel, the last of the batter, and the streusel with butter for the top of the cake. 

Bake for 50 to 60 minutes, until a toothpick comes out clean. Cool in the pan for 30 minutes. May be difficult to slice while still warm. Wrap in aluminum foil to serve.