In a large bowl or the bowl of a stand mixer, combine the butter and sugar until fully creamed together. Add the egg and vanilla and combine again.
Add the flour and baking powder and combine to form a soft cookie dough. Place this dough onto a large piece of baking paper. Add another large piece of baking paper on top and use a rolling pin to roll the dough to about 2cm thick. Place this sheet of dough into the fridge for at least 30 minutes.
Preheat the oven to 350℉/175℃. Line 3 large baking trays. Use a heart shaped cookie cutter to cut shapes in the dough and place on the lined baking sheets. They don't spread too much so can be placed fairly close together.
Bake for 10-12 minutes until just golden at the edges. Let cool on a wire rack.
Once cool, make the glaze by combining the powdered sugar and milk. Add a few drops of pink (or any) food colouring and swirl a little with a knife or end of a spoon.
Take a cookie, and dip the top (whatever will be the 'front'/top side of the cookie) into the glaze. Remove carefully, letting the excess icing drip off. Quickly flip the cookie and let set on a wire rack. If any has a little too much/too little icing, use that chopstick or similar to push around.
Repeat for all cookies, adding more colour when needed! Let set for at least an hour before serving!