Fold together egg yolks, butter, ricotta cheese and vanilla extract and put aside.
Whisk together flour, sugar, salt and lemon zest. With rubber spatula incorporate egg yolk and cheese mixture into flour mixture.
Whip egg whites into glossy peaks and gently fold into the batter.
Spray sauté pan with nonstick cooking spray. Over medium heat, make griddle cakes, being careful not to overcrowd the pan.
Makes 16-18 pancakes.Makes 5 to 6 Source: