For the Cookie Dough:
Make the Dough: In a large bowl, cream butter and sugar together until light and fluffy. Add egg and vanilla extract, mixing until combined.
Mix Dry Ingredients: In a separate bowl, whisk together flour, baking powder, and salt.
Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet ingredients, mixing until a dough forms.
Chill Dough: Wrap the dough in plastic wrap and chill for 30-60 minutes.
Roll and Cut: Preheat oven to 350°F (175°C). Roll out the dough on a floured surface to about 1/4-inch thickness. Cut out shapes using gnome-shaped cookie cutters or a simple triangle and circle for hats and faces.
Bake: Place cookies on a lined baking sheet and bake for 8-10 minutes, or until edges are lightly golden. Cool completely before decorating.
For the Royal Icing: