01 - Combine blueberries, sugar, water, and lemon juice in a small saucepan. Simmer over medium heat, stirring gently until berries burst and mixture thickens, about 8 to 10 minutes. For thicker syrup, dissolve cornstarch in 1 tsp water and stir in; cook for 1 to 2 more minutes. Remove from heat and keep warm.
02 - Whisk ricotta, egg yolks, milk, lemon zest, lemon juice, vanilla extract, and melted butter in a large bowl until smooth. In another bowl, mix flour, sugar, baking powder, baking soda, and salt. Stir dry ingredients into wet until just combined. Beat egg whites until soft peaks form; gently fold into batter.
03 - Heat a nonstick skillet or griddle over medium and brush lightly with butter. Pour 1/4 cup batter per pancake onto skillet. Cook 2 to 3 minutes until bubbles appear and edges set. Flip and cook another 1 to 2 minutes until golden and cooked through. Repeat with remaining batter, adding butter as needed.
04 - Stack pancakes on plates and spoon warm blueberry syrup over the top. Serve immediately.