In a large bowl, beat together the egg yolks, buttermilk, sugar, and ricotta cheese.
In a medium bowl, whisk together the flour, baking soda, baking powder, lemon zest, salt, and nutmeg (if using).
In a third bowl, beat the egg whites until stiff but not dry.
Mix the dry ingredients into the buttermilk mixture with a few quick strokes.
A few lumps remaining are okay.
Fold in the egg whites.
Heat a lightly greased griddle or skillet over medium heat.
Drop 1/4 cups of batter onto the preheated griddle.
Cook for about 2 1/2 minutes on the first side, bubbles should rise and burst.
Flip and cook on the second side for about 1 minute.
Should be light golden brown.
Serve with sauce.
Vanilla Sauce
Mix all of the ingredients until smooth in a small mixing bowl or blender. Thin with 1 tablespoon of milk if the vanilla sauce is too thick. Refrigerate until needed.
Make Ahead
The pancakes may be made a day ahead, cooled on a wire rack, then wrapped tightly and refrigerated. To reheat, preheat oven to 375, place pancakes on a lightly greased baking sheet, and heat for 5 minutes.