1. Combine sugar and cinnamon. Using pastry blender, cut in margarine. Add KELLOGG'S CORN FLAKES cereal and nuts. Mix until combined.
2. Prepare cake mix according to package directions.
3. Sprinkle half cereal mixture over bottom of 13 x 9 x 2-inch baking pan coated with cooking spray. Spread batter evenly over cereal mixture. Sprinkle with drained blueberries and remaining cereal mixture, pressing lightly into cake batter.
4. Bake at 350° F about 45 minutes or until wooden pick inserted near center comes out clean. Cool on wire rack in pan. Serve warm or cold.