This tender cake is both filled and topped with a delicious cinnamon-y streusel.

Cake
1/2 cup (4 ounces) butter
1 cup (7 ounces) sugar
2 large eggs
2 cups (8 1/2 ounces) King Arthur Unbleached All-Purpose Flour
1 teaspoon baking powder
1/4 teaspoon baking soda
1/2 teaspoon salt
1 cup (8 ounces) sour cream or yogurt*

*Feel free to use low-fat (NOT nonfat) sour cream or yogurt; if using yogurt, try vanilla or another complementary flavor, if desired.

Topping
1/2 cup (3 1/2 ounces) sugar
2 teaspoons ground cinnamon
2 teaspoons vanilla
1/2 cup (8 ounces) chopped walnuts, optional

Cream together the butter or margarine, sugar, and eggs. In a separate bowl, mix together the flour, baking powder, baking soda and salt. Add the flour mixture to the butter mixture alternately with the sour cream or yogurt, stirring after each addition.

Grease and flour a regular-sized (9 1/2-inch) tube pan or bundt-style pan, or a 9 x 9-inch pan. Spread half the batter in the pan, and sprinkle with half the topping mixture. Repeat with remaining batter and topping.

Bake the coffeecake in a preheated 350°F oven for 25 to 30 minutes, or until the cake tests done. Cool it for 10 to 15 minutes, then remove it from the pan. (If you've baked it in a 9 x 9-inch pan, just serve it right from the pan.) Place the cake right-side-up (topping up) on a plate to serve.
Yield: about 12 generous servings.