Preheat oven to 375°F. Place berries in 9-inch square baking pan.

Combine cake mix and cinnamon in large bowl. Add egg and 1/4 cup water; stir until well blended. Spoon over berries.

Combine sugar and cornstarch in small bowl. Stir in remaining 1/4 cup water until sugar mixture dissolves; pour over cake batter and berries. Do not stir.

Bake 40-45 minutes or until lightly browned. Serve warm or at room temperature with ice cream, if desired.