Separate eggs, placing whites in a very clean bowl and yolks in a large mixing bowl. Add milk, ricotta, sourdough starter, vanilla, lemon zest and juice to yolks. Whisk until reasonably smooth.
In a separate bowl, whisk together flour, sugar, baking powder, baking soda, and salt.
Pour wet ingredients into dry ingredients and stir until just combined. Gently mix in cooled melted butter - a few lumps are fine!
Using an electric mixer, beat egg whites until stiff peaks form, about 3-4 minutes.
Gently fold whipped egg whites into batter until no white streaks remain.
Heat skillet over medium. Pour ¼ cup batter per pancake. Immediately press blueberries into tops. Cook 3-4 minutes until bubbles form and edges set, then flip and cook 2-3 minutes more until golden.
Enjoy immediately with maple syrup, extra butter, and a sprinkle of lemon zest.