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American Flag Cake

American flag cake is a patriotic sheet cake made with two baked white layers, then frosted thick and topped with a clean blueberry canton and uniform strawberry red stripes. It’s finished with white frosting or banana slices for crisp, vivid red-white-blue rows—ideal for a 4th of July cake.
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Prep Time 45 minutes
Cook Time 35 minutes
cooling 1 hour
Total Time 2 hours 20 minutes
Servings: 20 servings
Course: Dessert
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

White cake mix
  • 2 boxes white cake mix Use the ingredients listed on the box for eggs, water, and oil.
Frosting
  • 2 cup unsalted butter Softened.
  • 6 cup powdered sugar
  • 2 tsp vanilla extract
  • 5 tbsp heavy cream Add 4–6 tbsp until spreadable.
Decoration
  • 2 cup fresh blueberries
  • 2 lb fresh strawberries Hulled and sliced lengthwise.
  • 1 banana slices Use banana slices (or extra white frosting) for the white stripes.
  • extra white frosting Optional alternative to banana slices for white stripes.

Equipment

  • 1 sheet pan

Method
 

Bake the sheet cake
  1. Preheat the oven and bake both white cake mixes in a large 12x18 sheet pan or two 9x13 pans joined together according to package directions, until a toothpick comes out clean and the tops spring back. Let the cakes cool completely before frosting.
Make the vanilla buttercream
  1. Beat the softened unsalted butter until fluffy, scraping the sides as needed for a light texture. Gradually add powdered sugar while mixing on low, then increase to medium and beat until smooth.
  2. Beat in vanilla extract and 4–6 tablespoons heavy cream, adding cream a tablespoon at a time until the frosting is thick, smooth, and spreadable with a spoon. Stop when it holds peaks softly.
Frost and decorate the flag
  1. Frost the entire top of the cooled sheet cake with a thick, even layer of white buttercream so it fully hides the cake surface. Use an offset spatula for a smooth top.
  2. In the upper left corner, arrange fresh blueberries into a dense rectangle to form the canton. Press the blueberries lightly so the shape stays crisp.
  3. Create red stripes by arranging sliced fresh strawberries flat across the length of the cake in straight rows. Keep the rows uniform in thickness from edge to edge.
  4. Fill the white stripes by piping extra frosting in rows between the strawberry rows or placing thin banana slices. Add straight lines so the red-white-blue pattern is clean and vivid.
Chill and serve
  1. Refrigerate the decorated cake until it is firm enough to slice, about 1 hour, and the fruit layers look set. Slice into squares and serve chilled for best structure.

Notes

Pro tip: For sharp stripes, keep strawberry rows tight with minimal gaps and pipe or place the white stripe base before adding extra fruit. Store covered in the refrigerator up to 3 days; fruit-on-top cakes don’t freeze well for texture. For a lighter option, use a reduced-fat buttercream style frosting, but keep the consistency thick so the design still holds.