Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.

In a bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream the softened butter and granulated sugar together using an electric mixer until light and fluffy.

Add the egg and vanilla extract to the butter mixture, and beat until well combined.

Gradually add the dry ingredients to the wet mixture, blending until a dough forms. Do not overmix.

Divide the dough into two portions, wrap in plastic wrap, and refrigerate for at least 30 minutes for easier rolling.

On a lightly floured surface, roll out one portion of the dough to about ¼-inch thickness. Use Easter-themed cookie cutters to cut out shapes and place them on prepared baking sheets.

Bake cookies in the preheated oven for about 10-12 minutes, or until the edges are lightly golden. Let them cool on the baking sheets for a few minutes before transferring them to a cooling rack to cool completely.

While the cookies are cooling, prepare the royal icing. If using egg whites, beat them until frothy, then gradually add the powdered sugar and lemon juice until smooth and spreadable. If using meringue powder, mix it with water according to package instructions and then combine with powdered sugar and lemon juice.

Divide the royal icing into small bowls and tint with food coloring as desired. Transfer the icing to piping bags or resealable plastic bags with a small hole cut in one corner.

Once the cookies are completely cool, decorate them with royal icing as desired. Allow the icing to dry completely before storing.

Store cookies in an airtight container at room temperature for up to one week.