In a large mixing bowl, whisk together egg yolks, ricotta cheese, lemon zest and juice, melted butter, milk, and vanilla until combined. Add pancake mix and stir until just incorporated.

In another bowl, beat egg whites with a whisk until soft peaks form. Using a spatula, gently fold egg whites into the batter until just combined. Do not overmix; batter will be lumpy.

Heat a griddle over medium heat and coat with cooking spray. Working in batches, ladle 1/4 cup of batter onto the griddle for each pancake. Cook until bubbles form on top and the pancakes are golden underneath, 2 to 3 minutes. Flip the pancakes and cook for about 2 minute more.

Serve immediately with warmed syrup and butter.