Preheat the oven to 350 degrees and line a 12 count muffin tin with cupcake liners.
Combine the 1/2 cup butter, 2 eggs, sugar, vanilla extract, baking powder, flour, and milk, mixing well.
Scoop about 1 1/2 tbsp. of each colored batter into the cupcake liners in the following order: red, white and blue. *You don't want to overfill the cupcake liners.
Bake 18-20 minutes. Insert a toothpick around 18 minutes. If it comes out 'clean' the cupcakes are done.
Remove from the oven and let cool completely prior to decorating.
Combine the powdered sugar, 1/3 cup softened butter, vanilla extract, and milk. Once the frosting has reached your desired consistency divide into 3 small dishes.
Add 1 drop of red gel food coloring to one bowl of frosting and stir to combine. Repeat this step with the blue gel food coloring.
Lay out a long piece of plastic wrap on the counter and a large baking sheet (you can always trim).
Fill one freezer bag with one color of frosting. Snip the corner using the kitchen scissors and gently squeeze the frosting out in a long line on the plastic wrap.
Repeat step previous step with the other 2 frosting colors.
Once all the frosting is lined up, gently roll the plastic wrap. Place in the fridge a few minutes to firm up.
Gently squeeze the frosting out of the bag and onto the cupcake in a circular motion.
Repeat with all cupcakes.