Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
In a medium bowl, whisk together flour, baking powder, and salt.
In a large bowl, beat the butter and sugar with an electric mixer until light and fluffy.
Add egg, lemon juice, and lemon zest to the butter mixture and mix well.
Gradually add dry ingredients to wet ingredients, mixing until just combined.
Drop rounded tablespoons of dough onto prepared baking sheets, spacing them 2 inches apart.
Bake for 10-12 minutes or until the edges are lightly golden. Remove from oven and allow to cool on the baking sheet for 5 minutes before transferring to a wire rack.
To prepare the glaze, whisk powdered sugar and lemon juice together until smooth. Add milk if the glaze is too thick.
Drizzle the lemon glaze over the cooled cookies and let set before serving.
Notes
Store cookies in an airtight container for up to 5 days. Perfect with a cup of tea or coffee!