This blueberry crisp captures a perfect balance between sweet summer blueberries and tart lemon flavors. Topped with a streusel laced with warming spices and baked to perfection, this is the perfect summer dessert paired with a scoop of vanilla ice cream. While we love fresh-picked blueberries, frozen blueberries work well too. Because they retain more liquid and are a little less sweet than fresh berries, be sure to increase the flour and sugar by 1 tablespoon each in the filling.