Blueberry Coffee Cake

1 1/2 cups all-purpose flour (about 6 3/4 ounces)
1 teaspoon baking powder
1/4 teaspoon baking soda
1/4 teaspoon salt
3/4 cup granulated sugar
6 tablespoons butter, softened
1 teaspoon vanilla extract
1 large egg
1 large egg white
1 1/3 cups low-fat buttermilk
Cooking spray
2 cups fresh blueberries
1 tablespoon turbinado sugar

Preheat oven to 350°.

Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, soda, and salt, stirring with a whisk.Place granulated sugar and butter in a large bowl; beat with a mixer at medium speed until well blended (about 2 minutes). Add vanilla, egg, and egg white; beat well. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with flour mixture; mix after each addition.

Spoon half of the batter into a 9-inch round baking pan coated with cooking spray. Sprinkle evenly with 1 cup blueberries. Spoon remaining batter over the blueberries; sprinkle evenly with remaining 1 cup blueberries. Sprinkle the top evenly with 1 tablespoon turbinado sugar. Bake at 350° for 50 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes on a wire rack; remove from pan. Cool completely on wire rack.

Original source: Cooking Light