Blueberry Buttermilk Coffee Cake

Streusel Topping:
2/3 cup packed brown sugar
1/2 cup flour
4 tablespoons cold butter

Mix above ingredients until crumbly.

Batter:
2 1/2 cups flour
1 1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 1/4 cups sugar
2 eggs
10 tablespoons softened margarine
1 teaspoon vanilla extract
1 1/4 cups buttermilk
1 pint (2 1/2 cups) blueberries

Beat sugar and margarine until blended on low speed. Increase speed to medium high and beat until creamy, about 2 minutes. Reduce speed and beat in eggs, one at a time. Beat well after each addition. Add vanilla extract. On low speed, beat in flour, baking powder, soda, salt and sugar alternately with the buttermilk. Fold in all but 1/2 cup blueberries. Pour into greased 9 x 13-inch pan. Sprinkle with reserved blueberries and sprinkle with streusel.

Bake at 350 degrees F for 30-40 minutes.