In a large mixing bowl, melt your butter for 30-60 seconds in the microwave. Most of the butter should be melted but some lumps should remain. Allow butter to cool for a few minutes.
¾ cup unsalted butter
Add sugar to melted butter and mix until well combined.
1 cup granulated sugar
Add eggs and vanilla to the butter and sugar. Whisk until well combined.
2 large eggs, 1 teaspoon vanilla extract
Next, add the lemon zest, lemon juice and lemon extract Whisk again. If you add the lemon flavors directly next to the eggs, the eggs will cook or curdle a little bit.
2 tablespoons lemon zest, 2 tablespoons lemon juice, ½ teaspoon lemon extract
Add flour, baking soda and salt to the wet ingredients. Mix until just combined.
2 cups (260g) all purpose flour, 1 teaspoon baking soda, 1 teaspoon salt
Fold in the frozen blueberries.
1 ½ cup fresh blueberries
Use a large cookie scoop to scoop the cookie dough into balls and arrange the cookie dough on a parchment lined sheet pan. Move tray to the refrigerator and chill the cookie dough for 30-60 minutes.
While dough is chilling, preheat oven to 350°.
Arrange the chilled balls of cookie dough on a parchment lined baking sheet leaving two inches of space between cookies. Bake cookies for 8-10 minutes or until the edges are just golden brown.
Remove from the oven. Allow cookies to cool on the baking sheet for 5-10 minutes before transferring to a wire rack.