This patriotic marble cake It keeps it nice and simple with a white cake mix tinted with a few drops of red and blue gel food coloring. Swirl them together in a pan, bake, then top with berries and airy Cool Whip frosting.
Preheat oven to 350°F. Spray a 9x13 glass baking dish with nonstick baking spray and set aside.
Beat together cake mix, egg whites, oil, and water until fully combined.
Divide the cake batter evenly into three bowls.
Tint one bowl of cake batter with the red food coloring and one bowl with the blue food coloring. Leave the third bowl white.
Drop large dollops of the cake batter throughout the prepared baking dish, rotating the colors. Use a knife to swirl the colors slightly - do not over swirl or the colors will become muddy and mixed.
Bake the cake for 25-30 minutes, until the cake is set and a toothpick comes out with just a few crumbs when poked in the center.
Allow the cake to cool completely.
Top the cake with the thawed Cool Whip and spread evenly.
Sprinkle berries over the top of the cake. Slice and serve.
Notes
To keep the white cake as white as possible, be sure to use egg whites and not whole eggs in your cake batter.
Use gel based food coloring to get the most vibrant color with the least amount of food coloring. We used Americolor Super Red and Americolor Sky Blue for this cake.
We used sliced strawberries, blueberries, blackberries, and raspberries. You can use any red or blue fruits you prefer to keep with the patriotic theme. You can alternatively top with sprinkles.
You can use a homemade stabilized whipped cream or a tub of Cool Whip. Regular homemade whipped cream will also work but does not hold up as well on top of cake. Buttercream frosting is another choice if you aren't a fan of whipped cream, which you can easily color with gel food coloring if desired.
To store - Cover your cake with plastic wrap or an air-tight lid and store it in the refrigerator for up to 5 days. If you are storing the cake without the cool whip and berries, you can keep it at room temperature covered with a lid or plastic wrap.
You can prepare, bake, and frost this cake a day in advance and store it covered in the refrigerator. If you plan on topping with berries I would suggest waiting until just before serving to add them as they can bleed their color into the Cool Whip topping after sitting for a while.
To freeze - You can easily freeze this cake by wrapping it a few times in plastic wrap followed by a layer of aluminum foil. Freeze for up to 3 months. Hold off on the berry topping if you plan on freezing.