1. Make the Dough

1. In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
2. In a large mixing bowl, cream the butter and sugar together using a hand or stand mixer on medium speed until light and fluffy, about 2–3 minutes.
3. Add the egg, vanilla extract, and milk. Beat until combined.
4. Gradually add the dry ingredients to the wet ingredients, mixing on low speed until a dough forms.
5. Divide the dough in half, shape into disks, wrap in plastic wrap, and refrigerate for at least 1 hour or up to 24 hours.

2. Roll and Cut

1. Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
2. On a lightly floured surface, roll out one disk of dough to about 1/4 inch thickness.
3. Use cookie cutters to cut out shapes, transferring them to the prepared baking sheets about 1 inch apart.
4. Re-roll scraps as needed and repeat with the second disk.

3. Bake

1. Bake cookies for 8–10 minutes, or until the edges are just barely golden. Do not overbake.
2. Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

4. Make the Royal Icing (Optional)

1. In a large bowl, whisk the powdered sugar and meringue powder together.
2. Add water 1 tablespoon at a time, mixing on low speed until the icing reaches your desired consistency.
3. Divide and color the icing as desired with gel food coloring. Use immediately or cover tightly.

5. Decorate

1. Once cookies are completely cooled, decorate with royal icing or other toppings like sprinkles, sanding sugar, or edible glitter.