Preheat your oven to 350°F (175°C).
In a bowl, whisk together the flour, baking powder, baking soda, and salt.
In a separate large bowl, cream the softened butter and sugar until light and fluffy.
Beat in the egg and vanilla extract until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Divide the dough into two portions, wrap in plastic wrap, and refrigerate for at least 1 hour.
Roll out the dough on a floured surface to about ¼ inch thick.
Use cookie cutters to cut out shapes and place them on a baking sheet lined with parchment paper.
Bake in the preheated oven for 10-12 minutes or until edges are lightly golden.
Allow cookies to cool completely before decorating with royal icing.