Preheat your oven to 350°F (175°C).
In a large mixing bowl, cream together the softened butter and sugar until light and fluffy.
Add the egg and vanilla extract, mixing until fully incorporated.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Chill the dough for at least 30 minutes in the refrigerator.
Roll out the dough on a floured surface to about 1/4 inch thick.
Cut out heart shapes using a cookie cutter and place them on a lined baking sheet.
Bake in the preheated oven for 8-10 minutes or until the edges are lightly golden.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack.
Once cooled, decorate the cookies with royal icing or fondant as desired.
