Preheat your oven to 350°F (175°C).
In a bowl, whisk together flour, baking powder, and salt.
In a separate bowl, cream the softened butter and sugar until light and fluffy.
Beat in the egg and vanilla extract until well combined.
Gradually mix in the dry ingredients until a dough forms.
Divide the dough into two parts, wrap in plastic, and refrigerate for 1 hour.
Roll out the dough on a floured surface to about ¼ inch thick.
Use cookie cutters to shape the dough into hearts and other designs.
Place the cookies on a baking sheet lined with parchment paper.
Bake for 10-12 minutes, or until the edges are lightly golden.
Let cool completely before decorating with royal icing.