01 - Preheat oven to 350°F. Line a 12-cup muffin pan with themed liners.
02 - In a bowl, whisk flour, baking powder, and salt until evenly combined.
03 - In a separate bowl, beat softened butter and granulated sugar with an electric mixer until pale and fluffy. Add eggs one at a time, beating thoroughly after each. Mix in vanilla extract.
04 - Add flour mixture in three batches, alternating with milk, starting and ending with flour. Mix until just combined. Do not overmix.
05 - Divide batter evenly among liners. Bake 18–20 minutes, or until a toothpick inserted in the center emerges clean. Allow cupcakes to cool completely on a rack.
06 - Beat room-temperature butter until creamy. Gradually add powdered sugar, then milk and vanilla. Beat on high speed until light and fluffy.
07 - Divide frosting into three bowls. Tint one bowl with red gel coloring and another with blue, leaving the third white.
08 - Fit a piping bag with a large star tip. Spoon alternating colors into the bag to create a swirl effect. Pipe tall swirls onto each cooled cupcake.
09 - Sprinkle cupcakes with red, white, and blue sprinkles and star-shaped candies. Add mini sparklers or patriotic toppers before serving; remove non-edible items prior to consumption.