Start by gathering all your ingredients and letting the cold butter sit out for a few minutes to soften slightly, but not too much.
In a large mixing bowl, use an electric mixer to cream together the cold butter and sugar until light and fluffy (about 3-5 minutes).
Add the egg and vanilla extract to the creamed mixture and mix until well combined.
In a separate bowl, whisk together the flour and baking powder. Gradually add this mixture to the wet ingredients, mixing on low speed until just combined.
Divide the dough into two equal portions, wrap each in plastic wrap, and refrigerate for at least 1 hour.
Preheat your oven to 350°F (175°C) while the dough chills.
On a lightly floured surface, roll out one portion of the dough to about 1/4 inch thick. Use a heart-shaped cookie cutter to cut out shapes and place them on prepared baking sheets.
Bake the cookies for 8-10 minutes, or until the edges are lightly golden. Keep an eye on them to prevent overbaking.
Let the cookies cool on the baking sheets for a few minutes before transferring them to a cooling rack. Decorate as desired or enjoy plain.
