If you don't have a 9-inch springform pan, you can bake this in a 9 x 1 1/2-inch round baking pan. Just reduce the amount of blueberries to 1 cup.

1 1/2 cups all-purpose flour
1 cup packed brown sugar
1 tsp. baking powder
1/2 tsp. baking soda
1/4 tsp. salt
1/4 tsp. ground cinnamon
1/2 cup butter or margarine
1 slightly beaten egg
1/2 cup buttermilk or sour milk
1 tsp. vanilla
1 1/2 cups blueberries
1/4 cup all-purpose flour
2 Tbsp. granulated sugar
2 Tbsp. butter or margarine
1 Tbsp. powdered sugar

Grease a 9-inch springform pan. Line bottom with waxed paper-, grease waxed paper. Flour pan; set aside.

In a large mixing bowl stir together the 1 1/2 cups flour, the brown sugar, baking powder, baking soda, salt, and cinnamon. Using a pastry blender, cut in the 1/2 cup butter until mixture resembles coarse crumbs. Make well in center of dry ingredients.

In a small mixing bowl combine egg, buttermilk, and vanilla. Add all at once to dry ingredients; stir just until moistened.

Spread batter in prepared pan. Top with blueberries. In a small mixing bowl stir together the 1/4 cup flour and granulated sugar. Cut in 2 tablespoons butter until mixture resembles coarse crumbs. Sprinkle over blueberries.

Place springform pan on a baking sheet. Bake in a 350 oven about 50 minutes or until a wooden toothpick inserted near center comes out clean. Cool cake in pan on wire rack for 30 minutes. Invert onto plate; remove waxed paper. Immediately invert again onto serving plate. Sprinkle with powdered sugar. Serve warm.