Preheat the oven to 350 degrees. Place 12 cupcake liners in a muffin tin.

In a medium bowl combine the flour, baking powder, and salt.

In a large bowl cream together the butter, sour cream, and sugar. Add in the egg and vanilla and mix well.

Add half the flour mixture to the butter mixture and mix well.

Add the milk to the butter mixture and mix until well combined.

Add the remaining flour mixture and mix until combined. Gently stir in the sprinkles.

Divide the batter between the muffin cups filling each one 3/4 of the way full.

Bake for 20 minutes.

Remove from oven and allow to cool 10 minutes before removing the cupcakes from the muffin tin and cooling completely on a wire rack.

To make the frosting place the butter in a bowl and beat with a mixer until creamy.

Add in the powdered sugar a half cup at a time, mixing after each addition, until desired consistency is reached.

Mix in the milk and vanilla and beat on medium high for 2 minutes. Add additional powdered sugar if needed.

To decorate the simple way place the frosting in a piping bag with a star tip and put a large swirl on each one. Sprinkle with the sprinkles.

To decorate the other way place 1/4 of the frosting in a zip top baggie and cut 1/2 inch off the end. Pipe a ring around the outer edge of each cupcake and dip into sprinkles.

Place the rest of the frosting in a piping bag with a star tip and pipe a swirl into the middle of each cupcake and top with a few more sprinkles.