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

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until well blended.

In a large mixing bowl, cream the softened butter and sugar on high speed for 1-2 minutes until light and fluffy.

Add the beaten egg and vanilla extract, mixing until pale and fluffy.

Gradually add the dry ingredients to the wet mixture, stirring until just combined.

Roll about 2 tablespoons of dough into balls and then roll each ball in granulated sugar.

Place the balls on the lined baking sheets, spacing them about 2 inches apart. Flatten each ball slightly.

Bake for 9-10 minutes, until the edges are set but the centers are slightly underbaked. Cool for 5 minutes before transferring to a wire rack.