Preheat oven to 340°F (170°C). Line a rectangular baking pan with parchment.
Cream the butter and sugar together until fluffy.
Beat in eggs, one at a time.
In a separate bowl, whisk flour, cocoa, and baking powder.
Alternate adding dry mixture and cream to wet ingredients, mixing until smooth.
Pour batter into the prepared pan. Bake 15-20 minutes or until a toothpick comes out clean.
Cool completely.
Spread whipped cream over the cooled cake.
Arrange blueberries in the top-left corner to represent the stars.
Place sliced strawberries in horizontal rows. Pipe whipped cream between rows for stripes.