Combine flour, fine sea salt, baking powder and baking soda in a bowl. Whisk well and set aside.
1 ¾ cup all purpose flour, ½ tsp fine sea salt, ½ tsp baking powder, ¼ tsp baking soda
In a large microwave safe bowl, add butter and melt until almost fully melted. Allow to cool.
10 tbsp unsalted butter, slightly melted and cooled
In a separate bowl, add sugar. Then zest the lemons onto the sugar and use fingers to rub zest and sugar together until it feels like coarse wet sand. Set aside.
¾ cup sugar, 2 lemons, for zest
Add lemon sugar, fresh squeezed lemon juice and lemon extract (optional) to butter. Whisk until well combined, about 1 minute.
1 tbsp fresh squeezed lemon juice, 1 tsp lemon extract
Add egg, whisk until well combined - about 1 minute.
1 large egg
Add dry ingredients, whisk until they are just combined.
Add blueberries. Use spatula to fold into dough carefully.
¾ cup frozen wild blueberries
Preheat oven to 350 F. Use 2 tablespoon scoop to scoop cookies and place on baking sheet at least 3" apart. Place 5 to 6 cookies per sheet.
Bake for about 13 minutes, or until you begin see edges browning and the top of the cookie looks matte. Remove from oven and allow to cool for a few minutes before rolling in lemon sugar.