While the cupcakes are cooking, prepare the frosting.
In a large bowl, beat the butter and vanilla until creamy.
Gradually add the powdered sugar.
Add the milk or heavy cream until frosting reaches the desired consistency.
Split the buttercream into 3 colors.
Following the same instructions as the batter dye the frosting red and blue.
Place each color into a piping bag and snip the ends.
Prep a separate piping bag with a 1M tip .
Add the 3 piping bags with the colored frosting into the bag with the piping tip. This will create a tri-color frosting.
Pipe a star into the center of the cupcake.
Then without releasing pressure pipe a swirl around that tip, applying even pressure.
Release the pressure when you are about to complete the circle around the center star and then pull away. Repeat for each cupcake.