Heat the oven to 325°F / 160°C.

In a bowl, combine the flour, sugar, baking powder, salt, and butter. Beat with an electric mixer at low speed until everything is incorporated and the mixture resembles coarse sand.

Gradually add half of the milk and continue beating until combined.

Mix in the egg, vanilla, and remaining milk, adding it to the mixture while continuing to beat until smooth; do not overbeat.

Pour the batter into a cupcake pan lined with paper liners and bake for 20 to 25 minutes, or until golden brown. Test for doneness by inserting a toothpick; if it comes out clean, they are ready.

Transfer the cupcakes to a wire rack to cool completely before decorating.

In a small saucepan, place the sugar, water, cream of tartar, and salt, and bring to a boil over medium heat, stirring until the sugar is completely dissolved.

In the bowl of a stand mixer, place the two egg whites, turn on the mixer, and gradually add the prepared syrup, beating until stiff peaks form and the bowl cools down, about 7 minutes.

Add the vanilla and food coloring if using, and beat a little longer until combined. Decorate the cupcakes, serve, and enjoy!