In a small bowl, whisk together the cake flour, salt and cocoa powder. Set aside. Combine the sugar and oil with an electric mixer, beating until well combined. Add the egg and mix well. Add the food coloring and vanilla extract and mix until combined. Add the flour mixture in 2 additions, alternating with the buttermilk.

In a small bowl, combine the baking soda and vinegar, then add to the batter and mix to combine. Divide the mixture between a greased and floured small cake pan and small stainless steel mixing bowl. Bake at 350F for 30-50 minutes, until a knife inserted into the middle of the cakes comes out clean. Cool for 5 minutes in the pan, then turn out onto a cooling rack and cool completely.

Cream the butter with an electric mixer until pale and fluffy. Add the vanilla extract and mix until combined. Add the confectioner’s sugar one cup at a time, then beat for 2-3 minutes until fluffy.

Remove about 1 cup of buttercream and divide it into 2 bowls. Dye one bowl red and one bowl blue. Place them in piping bags fitted with 1D basketweave piping tips, or any flat piping tip you like!

Stack the round cake on top of the flat cake and carve so that the base is more narrow than the round cake. Pipe red and blue stripes on the cupcake base, then swirl the white buttercream on top. Decorate with red and blue candies and enjoy!