Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a large mixing bowl, cream together the softened butter and sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition. Stir in the milk and vanilla extract until combined.

In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Divide the batter evenly into three bowls. Leave one bowl plain, add red food coloring to the second bowl, and blue food coloring to the third bowl. Mix until the colors are vibrant.

Spoon a tablespoon of each colored batter into the cupcake liners, layering them to create a striped effect.

Bake in the preheated oven for 18-20 minutes or until a toothpick inserted into the center comes out clean. Allow the cupcakes to cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

Once cooled, frost the cupcakes with vanilla frosting and sprinkle with red, white, and blue sprinkles.