Preheat your oven to 350°F (175°C).
Grease and flour three 9-inch round cake pans.
In a large mixing bowl, cream together the softened butter and sugar.
Add the eggs one at a time, mixing well after each addition.
Stir in the buttermilk and vanilla extract until combined.
In a separate bowl, whisk together the flour and baking powder.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Divide the batter evenly among the prepared pans.
Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes before transferring to a wire rack.
Once cooled, frost between the layers and on the top with whipped cream.
Decorate the top with halved strawberries and blueberries to create a flag design.
Chill the cake for at least 30 minutes before serving.
