01 - Whisk together flour, baking powder, and salt in a medium bowl. Set aside for later use.
02 - Beat softened butter and granulated sugar in a large mixing bowl until light and fluffy, approximately 2–3 minutes.
03 - Add egg and vanilla extract to the butter mixture. Beat until fully incorporated.
04 - Gradually mix dry ingredients into wet ingredients on low speed. Add milk and continue mixing until dough forms a cohesive ball.
05 - Divide dough into two equal portions. Flatten each into a disk, wrap tightly in plastic wrap, and refrigerate for at least 1 hour.
06 - Preheat oven to 350°F. Line baking sheets with parchment paper and set aside.
07 - On a lightly floured surface, roll one dough disk to 1/4-inch thickness. Cut out egg shapes using a cookie cutter and arrange on prepared baking sheets, leaving space between cookies.
08 - Bake for 8–10 minutes until edges are just beginning to turn golden. Allow cookies to cool on baking sheets for 5 minutes, then transfer to a wire rack to cool completely.
09 - Combine powdered sugar, meringue powder, and warm water in a bowl. Mix until smooth and thick but pipeable. Divide icing into separate bowls and tint each with food coloring.
10 - Fill piping bags or zip-top bags with the corner snipped off with colored icing. Decorate cooled cookies as desired. Allow icing to set completely before serving or storing.