In a mixing bowl, whisk the flour, baking powder and salt together until well combined.
Using a stand mixer fitted with paddle attachment or electric hand mixer with beaters, mix the granulated sugar and lemon zest together until they are the consistency of wet sand.
Cream the room temperature butter and lemon sugar until well combined. This takes about 3 - 4 minutes on medium speed. On low, mix in the egg, extract and lemon juice until smooth and well combined.
Mix the dry ingredient into the wet ingredients until just combined. Cover the dough and chill in the fridge for 30 - 60 minutes.
While the cookies chill, preheat the oven to 350 F (177 C). Line two large baking sheets with parchment paper.
Scoop about 1 tablespoon (15 ml) of cookie dough 2 inches apart onto the prepared baking sheet.
Bake the lemon drop cookies for 11 - 13 minutes. The bottom of the cookies will be very lightly golden brown.
Remove the cookies from the oven onto a cooling rack. After 3 - 4 minutes, transfer the cookies off the hot baking sheet and onto the cooling rack to cool to room temperature.
Make the lemon glaze for the lemon drop cookies by mixing 2 - 3 tablespoons (30 ml) lemon juice with 1 ½ cups (180 g) of powdered sugar until well combined.
Top each cookie with the lemon glaze.
