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