Preheat your oven to 375°F (190°C).

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

Beat in the egg yolk and vanilla extract until fully combined.

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

Fill a cookie press with dough and press onto ungreased baking sheets in your desired shapes. Top each cookie with colored sprinkles.

Bake for 8-10 minutes or until the edges are lightly golden. Allow to cool before serving.