Preheat your oven to 350°F (175°C).
In a bowl, whisk together flour, baking powder, and salt.
In another bowl, cream the softened butter and sugar until light and fluffy.
Add the egg and vanilla extract to the butter mixture, mixing well.
Gradually add the dry ingredients to the wet mixture, combining until a dough forms.
Roll out the dough on a floured surface to about 1/4 inch thick.
Cut shapes using cookie cutters and place them on baking sheets lined with parchment paper.
Bake for 10-12 minutes until edges are lightly golden.
Allow cookies to cool completely before decorating.
For royal icing, mix powdered sugar and meringue powder with water until smooth.