Preheat the oven to 350°F (175°C). Grease and flour the cake pans.

In a mixing bowl, combine flour, sugar, baking powder, baking soda, and salt.

Add softened butter, eggs, vanilla extract, and milk. Mix until smooth.

Divide the batter into two bowls. Color one with red food coloring and the other with blue food coloring.

Pour the red batter into one pan and the blue batter into the other. Bake for 25 minutes or until a toothpick comes out clean.

Let the cakes cool in the pans for 10 minutes, then transfer to a cooling rack.

In a mixing bowl, beat the softened butter until creamy. Gradually add powdered sugar, milk, and vanilla extract.

Once the cakes are completely cool, frost the top of the blue cake and place the red cake on top.

Frost the top and sides of the stacked cake.

Decorate with blueberries and sliced strawberries to create a flag design.

Slice and serve to celebrate Flag Day!