Preheat oven to 350°. Spray baking sheets with baking spray with flour.

In a large bowl, beat butter, granulated sugar, and vanilla with a mixer at medium speed until creamy, 3 to 4 minutes, stopping to scrape sides of bowl. Add egg, beating well. In a medium bowl, whisk together flour and salt. Gradually add flour mixture to butter mixture, beating just until combined.

Divide dough into 2 equal portions. Shape each portion into a disk. Wrap in plastic wrap, and refrigerate for 10 minutes.

On a heavily floured surface, roll one dough disk to 1/8-inch thickness. Using a 3-inch heart-shaped cutter, cut dough, rerolling scraps as necessary. Place 2 inches apart on prepared pans. Repeat with remaining dough. Bake until edges are lightly browned, 10 to 12 minutes. Let cool on pans for 5 minutes. Remove from pans, and let cool completely on wire racks.

In a medium bowl, whisk together confectioners’ sugar, meringue powder, and ¼ cup water. Brush cookies with mixture, and sprinkle with edible glitter.