Preheat your oven to 350°F. Line a baking sheet with parchment paper or silicone baking mats.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a large mixing bowl, beat the softened butter, sugar, and the lemon zest until everything has been well creamed together, about 2 minutes. Next, using the whisk attachment beat in the egg, lemon juice, and vanilla extract until well combined and slightly fluffy.
Gradually add the dry ingredients into the wet ingredients until just combined. Be careful not to overmix.
Gently fold in the blueberries with a spatula, being gentle so they don’t get smashed and turn the dough purple.
Using a 1-inch cookie scoop or spoon, drop a round ball of dough onto the prepared baking sheets, making sure to leave about 2 inches of space between each cookie. Bake for 12-15 minutes, or until the edges are lightly golden. The centers may still look slightly soft.
Allow the cookies to cool on the baking sheet for about 5 minutes, before transferring them to a wire rack to cool completely.
Optional: In a small bowl, whisk together the powdered sugar, lemon juice, and lemon zest until smooth. Drizzle the glaze over the completely cooled cookies.
Let the glaze set for a few minutes before serving.