Blueberry Mascarpone Macarons

Name: Blueberry Mascarpone Macarons
Prep time: 2 h
Cook time: 15 min
Total time: 2 h 15 min
Cuisine: French
Ingredients: 150 grams blueberries (fresh or frozen); 2 tablespoons granulated sugar; 1 1/2 teaspoons cornstarch; 2 teaspoons lemon juice; 1/2 teaspoon lemon zest (optional ); 100 grams egg whites (room temperature); 1/4 teaspoon cream of tartar; 60 grams granulated sugar; 110 grams almond flour (sifted); 200 grams powdered sugar (sifted); 1-2 drops purple gel food coloring (optional ); 125 grams mascarpone cheese (room temperature); 42 grams powdered sugar; 1/2 teaspoon lemon juice