01 - Whisk together flour, baking powder, and salt in a medium bowl. Set aside.
02 - Beat butter and sugar in a large bowl until light and fluffy, approximately 2–3 minutes.
03 - Add egg and vanilla extract. Beat until fully incorporated.
04 - Gradually mix in dry ingredients until a soft dough forms.
05 - Divide dough in half, shape into discs, wrap in plastic wrap, and refrigerate for minimum 1 hour.
06 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
07 - On lightly floured surface, roll dough to 1/4-inch thickness. Cut heart shapes with cookie cutters.
08 - Place cookies 1 inch apart on prepared baking sheets.
09 - Bake for 8–10 minutes until edges begin turning golden. Cool completely on wire racks.
10 - Beat powdered sugar, meringue powder, and 3 tablespoons water until stiff peaks form. Adjust consistency with additional water as needed for piping or flooding.
11 - Tint icing with gel food coloring if desired.
12 - Decorate cooled cookies with royal icing. Allow icing to set completely at room temperature before serving or packaging.