Preheat the oven to 350°F (175°C).
In a mixing bowl, cream the softened butter and sugar until light and fluffy.
Beat in the egg and vanilla extract until well combined.
In another bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Using a cookie scoop or your hands, form small balls of cookie dough and place them on a lined baking sheet.
Sprinkle the extra granulated sugar evenly over the top of each dough ball.
Bake for 12-15 minutes, or until the edges are lightly golden.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.