Double Berry Streusel Topped Cake

Preheat oven to 400 F. Grease bottom of 13x9x2-inch baking pan or coat with nonstick cooking spray; set aside. In medium mixing bowl stir together 2 cups flour, 1/4 cup sugar, baking powder, and salt. Cut in 6 tablespoons butter until mixture resembles coarse meal; set aside. In small bowl stir together milk, egg, and vanilla; add to flour mixture stirring until moistened. Fold in blueberries. Spread evenly in prepared pan (batter will be thin in pan). Spoon undrained strawberries over batter in pan. In another small bowl stir together 1/3 cup flour and 3 tablespoons sugar. Cut in 3 tablespoons butter until mixture resembles fine crumbs. Sprinkle over berries. Bake 25 to 30 minutes or until set and top is evenly browned. Cool about 30 minutes before serving. Serve with whipped cream.