Preheat the oven to 350?F (175?C).

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

Beat in the egg and vanilla extract until well combined.

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

Gradually add the dry ingredients to the wet mixture, mixing until a dough forms.

Roll out the dough on a floured surface to about 1/4 inch thick.

Use cookie cutters to cut out shapes and place them on a baking sheet lined with parchment paper.

Bake for 8-10 minutes or until the edges are lightly golden.

Allow cookies to cool completely on a wire rack.

In a bowl, mix the powdered sugar, milk, and vanilla extract until smooth.

Add food coloring if desired and mix until the color is uniform.

Drizzle or spread the icing over the cooled cookies and top with sprinkles.