01 -
Preheat the oven to 375°F (190°C) for about 20-30 minutes. Line a large baking sheet with parchment paper.
02 -
Melt the butter in a small bowl and allow it to cool in the fridge for about 10 minutes.
03 -
In a separate bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt until thoroughly combined.
04 -
In a large mixing bowl, whisk together the sugar and lemon zest until the consistency resembles wet sand. Whisk in the cooled, melted butter, followed by the egg, egg yolk, and vanilla extract until the mixture is smooth and uniform.
05 -
Gradually stir the dry ingredients into the wet mixture until just combined. Gently fold in the fresh blueberries.
06 -
Use a medium cookie scoop (approximately 2 tablespoons or 30 ml) to form cookie dough balls. If desired, roll the cookie dough in granulated sugar before placing on the prepared baking sheet, leaving about 3 inches (8 cm) between each ball.
07 -
Bake the cookies at 375°F (190°C) for 10-12 minutes, or until the edges are set and lightly golden brown.
08 -
Allow the cookies to cool on the baking sheet for 3-4 minutes before transferring them to a cooling rack to cool completely. Serve and enjoy!