Preheat your oven to 350°F (175°C).

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

Beat in the egg and vanilla extract until well combined.

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

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

Divide the dough into two halves and wrap each in plastic wrap. Chill for at least 1 hour.

Roll out the chilled dough on a floured surface to about ¼ inch thick.

Use heart-shaped cookie cutters to cut out cookies and place them on a baking sheet lined with parchment paper.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden.

Allow cookies to cool completely before decorating with royal icing and sprinkles.