Preheat the oven to 180C/350F/Gas 4, and line a baking tray with parchment paper, or a silicone mat. Set aside.
Whisk together the flour, baking powder, cornflour, baking soda, salt, and lemon zest. Set aside.
Whisk together the butter, cream cheese, and sugar. Add the egg and mix until combined, then mix in the lemon extract. Fold in the dry ingredients.
Roll the dough into 1.5oz balls, about 14 - 15 balls, and place on the prepared baking tray. Bake for 10 - 12 minutes.
Allow to cool on the baking tray for 5 minutes before transferring to a wire rack to cool completely.
For the Glaze
Mix together the icing sugar and lemon juice until smooth and combined. Add more juice to reach desired consistency if needed.
Drizzle the glaze over the cooled cookies, and enjoy!
Notes
Cookies stay fresh, kept in an airtight container, at room temperature for up to 1 week.Cookie dough balls can be kept in the fridge for up to 5 days, or frozen for up to 3 months. Bake from frozen for an extra minute.