In a stand mixer with a paddle attachment, beat sugar and butter until light and fluffy, around 2-3 minutes. Add egg and vanilla extract and mix until combined for 15-30 seconds.

Whisk together flour, baking powder, and salt in a medium bowl. Gradually add this mixture to the sugar mixture and beat on low speed for about 1 minute until just combined.

Divide the dough into 2 discs, wrap in plastic wrap, and refrigerate for at least 1 hour or up to 1 day.

Preheat the oven to 350°F (175°C). Remove one disc of dough and roll out on a floured surface to 1/4-inch thickness. Cut shapes using Easter-themed cookie cutters and place on prepared baking sheets.

Bake cookies for 8-10 minutes and let them cool on baking sheets for 5 minutes before transferring to a wire rack to cool completely for 30 minutes.

To prepare Royal Icing, beat powdered sugar and meringue powder with water and vanilla extract in a stand mixer for about 15 seconds until smooth. Adjust consistency if needed.

Divide icing into bowls, add food coloring, and transfer to piping bags. Outline cookies, fill with icing, and let dry for about 1-2 hours.