Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. Mix in the egg and vanilla extract until well combined.

In another bowl, whisk together the flour, baking powder, and salt. Gradually add this mixture to the wet ingredients, mixing until just combined.

Roll out the dough on a floured surface and cut out heart shapes using cookie cutters. Place them on the prepared baking sheets about an inch apart.

Use a toothpick or knife to mark your hearts with X's and O's.

Bake for 10-12 minutes or until edges are lightly golden. Cool on wire racks before serving.