Toss blueberries with 1 tablespoon flour and set aside.
Cream butter, granulated sugar, and brown sugar until light and fluffy.
Beat in egg, vanilla, lemon zest, and lemon juice.
Whisk together flour, baking powder, baking soda, and salt.
Gradually mix dry ingredients into the wet ingredients until just combined.
Gently fold in blueberries and add blue food coloring to reach your desired shade.
Chill dough for 30–45 minutes.
Preheat oven to 350°F and line a baking sheet with parchment.
Scoop approximately 1½ tablespoons of dough per cookie.
Bake for 10–12 minutes, until edges are set and centers remain slightly soft.
Cool completely.
Whisk together frosting ingredients and tint blue.
Spread frosting over cooled cookies.
Finish with blue circle sprinkles and blue sparkling sugar.
Enjoy!