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

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

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, alternating with the milk, and mix until just combined.

Divide the batter evenly among the cupcake liners, filling each about 2/3 full.

Bake for 15-18 minutes or until a toothpick inserted into the center comes out clean.

Allow the cupcakes to cool completely on a wire rack.

In a mixing bowl, beat the softened butter until creamy.

Gradually add the powdered sugar, mixing on low speed until combined.

Add the milk and vanilla extract, and beat on high speed until the frosting is light and fluffy.

Once the cupcakes are completely cool, frost them generously with the buttercream frosting.

Top each frosted cupcake with colorful sprinkles.