01 - Set oven to 350°F and line a 12-cup muffin tin with patriotic liners.
02 - Whisk together flour, baking powder, and salt in a mixing bowl.
03 - In a separate bowl, beat unsalted butter and granulated sugar until light and fluffy, then add eggs one at a time. Blend in vanilla extract.
04 - Add flour mixture in three parts, alternating with whole milk, beginning and ending with the dry ingredients. Mix just until combined.
05 - Divide batter evenly among liners and bake for 18 to 20 minutes, until an inserted toothpick emerges clean. Allow cupcakes to cool completely.
06 - Beat unsalted butter until creamy. Gradually blend in powdered sugar, followed by milk and vanilla, beating on high speed until fluffy.
07 - Divide the frosting into three portions. Tint one red, one blue, and keep one white. Fill a piping bag fitted with a large star tip with spoonfuls of each color to achieve a swirl effect.
08 - Pipe high swirls onto cooled cupcakes. Adorn with red, white, and blue sprinkles and star-shaped candies. Add sparklers or themed toppers before serving; always remove before eating.