DirectionsPreheat oven to 350 F. Cream butter and 1 cup sugar. Add eggs one at a time, beating after each addition. Sift together four, salt, baking powder and baking soda. Add to creamed mixture. Blend in sour cream and vanilla. Batter will be stiff.
Pour batter into greased 10-inch springform pan. Combine cinnamon with remaining ½ cup sugar. Sprinkle half of cinnamon-sugar mixture over batter. Insert knife and make zigzag movements through butter to marbleize. Smooth top.
Sprinkle blueberries evenly over butter. Arrange half of strawberries decoratively around outer edge, spoke-fashion. Sprinkle remaining strawberries over blueberries. Pat berries gently into batter so they are one-half submerged.
Sprinkle with remaining cinnamon-sugar mixture. Bake in preheated 350 degrees oven 50 to 60 minutes, or until lightly browned around edges and tester inserted in center comes out clean. Cool in pan on rack 30 minutes. Remove pan sides and cool completely.