1/2 cup soft butter
1 cup granulated sugar
3 eggs
2 cups sifted flour
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon salt
1 cup sour cream
1 teaspoon vanilla extract
2 cups blueberries, divided
1/2 cup brown sugar, firmly packed

Preheat oven to 325 degrees F. Grease well and flour a 13 x 9-inch baking pan.

Cream butter and sugar. Add eggs one at a time, beating well after each addition.

Sift dry ingredients together. Gradually add to egg mixture, alternating with sour cream, ending with flour mixture. Stir in vanilla extract. Fold in 1 cup blueberries. Pour half the batter into prepared baking pan. Cover with remaining 1 cup blueberries. Sprinkle with brown sugar, then top with remaining batter. Bake for 45 to 50 minutes. Cool in pan for 10 minutes. Remove to rack to finish cooling.

Serves 12.