Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper or a silicone baking mat.
In a medium-sized bowl, cream together the softened butter and granulated sugar using a hand mixer or a whisk until light and fluffy (about 1 minute). Then, beat in the egg, lemon zest, and lemon juice until well combined.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix.
Using a spoon or your hands, scoop tablespoon-sized portions of dough and roll them into balls. Place the dough balls on the prepared baking sheet, spacing them about 2 inches apart. For a slightly flatter cookie, gently press each dough ball with the back of a spoon.
Bake the cookies in the preheated oven for 8-10 minutes, or until the edges are golden but the centers are still soft.
Allow the cookies to cool on the baking sheet for a couple of minutes before transferring them to a wire rack to cool completely. Optionally, dust the cooled cookies with powdered sugar for a lovely finish.
