01 - Whisk together flour, baking powder, and salt in a medium bowl until thoroughly combined.
02 - Beat softened butter and granulated sugar with an electric mixer on medium-high speed for 2-3 minutes until mixture appears pale and fluffy.
03 - Add egg and vanilla extract to the butter mixture. Beat on medium speed until fully incorporated and smooth, scraping down bowl sides as needed.
04 - Gradually add dry ingredient mixture to the wet ingredients on low speed, mixing just until a uniform dough forms without overmixing.
05 - Divide dough into two equal portions. Flatten each into a 1-inch thick disc, wrap tightly in plastic wrap, and refrigerate for minimum 1 hour to firm.
06 - Set oven to 350°F. Line two large baking sheets with parchment paper.
07 - On lightly floured work surface, roll one dough disc to 1/4-inch thickness. Cut heart shapes using cookie cutter and arrange 2 inches apart on prepared baking sheets.
08 - Gather remaining dough scraps, re-roll to 1/4-inch thickness, and cut additional shapes. Repeat process with second dough disc until all dough is used.
09 - Bake one sheet at a time for 8-10 minutes until edges show faint golden color. Let cookies rest on baking sheet for 5 minutes before moving to wire rack.
10 - Whisk powdered sugar, 2 tablespoons milk, and vanilla extract in small bowl until completely smooth. Adjust consistency with additional milk if needed. Add food coloring as desired.
11 - Once cookies have cooled completely, spread or drizzle glaze over each cookie and immediately top with sprinkles. Allow glaze to set for 20 minutes before serving or storing.