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

In a mixing bowl, cream together softened butter, granulated sugar, and brown sugar until light and fluffy.

Beat in the egg and vanilla extract until well combined.

In another bowl, whisk together flour and salt; gradually mix into the wet ingredients until just combined.

Roll out dough to 1/4 inch thick on a floured surface and cut into heart shapes using cookie cutters.

Place on baking sheets and bake for 10-12 minutes or until edges are lightly golden. Cool on wire racks.