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 teaspoon water, stir into syrup, and cook 1 to 2 more minutes. Remove from heat and keep warm.
02 - In a large bowl, whisk ricotta, egg yolks, milk, lemon zest, lemon juice, vanilla, and melted butter until smooth. In a separate bowl, mix flour, sugar, baking powder, baking soda, and salt. Gently fold dry mixture into wet ingredients until just combined. Beat egg whites until soft peaks form and fold gently into batter.
03 - Heat a nonstick skillet or griddle over medium heat and brush lightly with butter. Pour 1/4 cup batter per pancake onto skillet. Cook until bubbles form and edges set, about 2 to 3 minutes. Flip and cook 1 to 2 minutes more 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.