In a separate bowl, whisk flour, baking powder, and salt.
Add dry ingredients to wet ingredients and mix until dough forms.
Cover and refrigerate overnight.
Preheat oven to 400°F.
Roll chilled dough on a lightly floured surface and cut into shapes.
Place cookies on parchment-lined baking sheets.
Bake 7 to 8 minutes, until set but not browned.
Cool completely.
Mix frosting ingredients until smooth and tint with food coloring if desired.
Frost and decorate cooled cookies.
Notes
Chill the dough overnight so it rolls cleanly and holds its shape. Pull cookies when they look just set; they firm up as they cool. Use parchment or a silicone mat for even baking. Freeze unfrosted cookies and decorate later for easier holiday prep.