• Beat the butter with the sugar in a stand mixer with the paddle attachment (or with a hand mixer) until light and creamy, about 4 to 5 minutes.
  2 sticks unsalted butter, ⅔ cup sugar
• Beat in the vanilla and then the egg.
  1½ teaspoon vanilla extract, 1 large egg
• With the mixer on medium-low, slowly add the flour, salt, and baking powder. Beat until fully mixed.
  2½ cup all-purpose flour, ½ teaspoon salt, ¼ teaspoon baking powder
• Remove the dough and smooth it into a ball with your hands. Divide the dough into three discs, cover with plastic wrap, and refrigerate for 30 minutes (or up to overnight).
• Preheat oven to 350°F.
• Working 1 portion at a time, roll the dough out on a lightly floured surface to about ¼ to ½-inch thickness. Cut the cookies with the cutters. Gather the scraps and reroll to cut more cookies. Place the cookies on two sheet pans lined with a silicone mat or parchment paper. Bake until the edges are just starting to turn a light brown, about 13 to 15 minutes.
• Allow the cookies to cool completely before icing them.

Make the Royal Icing

• In a large bowl, add the confectioners' sugar, meringue powder, hot water, and vanilla extract.
  4 cups confectioners' sugar, 3 tablespoon meringue powder, ½ cup hot water, ½ teaspoon vanilla extract
• Use an electric mixer on medium speed and beat until thick, about 7 minutes. You'll know it's ready when you can drag a spoon across the top of the icing and a ribbon remains on the surface.
• Divide the icing and stir in desired food coloring gels. Ice cookies with a small spatula, coffee stirrer, or toothpick. Decorate with icing bottles.