Heat oven to 350 degrees. Prepare cake mix as directed on package, adding vanilla.
Transfer 1-1/2 cups batter to small bowl and tint with neon blue food color. Tint remaining batter red by adding cocoa powder and red food color. Pour each color batter into separate 9-by-5-inch loaf pans sprayed with nonstick cooking spray.
Bake blue-tinted cake for 20-25 minutes, and red-tinted cake for 30-35 minutes. Cool cakes in pans 10 minutes.
Remove from pans; cool completely. Trim cakes to remove rounded tops and edges. Slice red cake in half horizontally to form two thin layers. Place one layer on platter. Slice remaining red cake layer in half lengthwise. Slice blue cake in half lengthwise. (Blue and red cakes should be same dimensions.) Frost red cake layer on platter with 1/3 of the frosting.
Top with lengthwise slices of red and blue cake side-by-side. Frost with 1/3 frosting. Repeat cake layer and frosting. Garnish with raspberries and blueberries to resemble a flag.
All materials courtesy of Family Features. Find more recipes and ideas to fireup your Fourth of July at www.mccormick.com