01 -
Preheat the oven to 375°F (190°C) for about 20-30 minutes before baking the cookies. Line a large baking sheet with parchment paper.
02 -
In a small bowl, melt the butter and cool in the fridge for about 10 minutes.
03 -
In another bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt until well combined.
04 -
In a large mixing bowl, whisk the sugar and lemon zest together until they resemble the consistency of wet sand. Whisk in the cooled melted butter until well combined. Then whisk in the egg, egg yolk, and vanilla extract until smooth.
05 -
Stir the dry ingredients into the wet ingredients until just combined. Gently stir in the fresh or frozen blueberries until evenly mixed.
06 -
Using a medium cookie scoop (2 tablespoons, 30 ml), form balls of lemon blueberry cookie dough. If rolling in sugar, coat the balls in sugar and place them on the lined baking sheet spaced about 3 inches (8 cm) apart.
07 -
Bake at 375°F (190°C) for 10-12 minutes or until the edges are set and lightly golden brown.
08 -
Cool the cookies on the baking sheet for 3-4 minutes before transferring them to a cooling rack to cool completely. Enjoy!