Preheat the oven to 350°F (175°C). Line baking sheets with parchment paper.

Whisk together the flour, baking powder, and salt in a medium bowl. Set aside.

In a large bowl, cream the softened butter and granulated sugar with a mixer on medium speed until light and fluffy, about 2–3 minutes. Scrape down the sides once.

Beat in the egg and vanilla until fully incorporated and smooth.

Gradually add the dry ingredients to the wet ingredients, mixing on low until just combined. Don’t overmix — stop when the dough looks uniform.

Shape the dough into a disk, wrap in plastic, and chill in the refrigerator for 30 minutes.

Lightly flour your work surface and roll the dough to about ¼ inch thick. Keep unused dough chilled.

Use heart-shaped cookie cutters to cut out cookies. Transfer shapes to the prepared baking sheets, spacing about 1–2 inches apart.

Bake for 10–12 minutes, or until the edges are just turning a light golden color.

Let cookies cool on the baking sheet for a few minutes, then transfer to a wire rack to cool completely before icing.

Whisk powdered sugar with milk until smooth. Add food coloring a drop at a time until you reach the desired hue.

Decorate cookies as desired with a spoon, spatula, or piping bag. Let icing set fully before stacking or packing.