Mix the ricotta cheese, egg yolks, sugar, orange zest, orange juice, and buttermilk in a large bowl.
In a separate bowl, mix the flour, baking powder and salt.
Combine the wet and dry ingredients, being careful not to over-mix; it is OK if there are a few lumps in the mixture.
Meanwhile, beat the egg whites in a bowl until soft peaks just start to form.
Gently fold the egg whites into the pancake batter, being careful not to deflate the egg whites.
Heat a nonstick skillet over medium-low heat and add 1/2 tablespoon of butter.
Pour about 1/8 cup of the pancake batter in the pan and cook until they start to bubble (about 2 minutes).
Flip and cook the other side for about 1-2 minutes. Pancakes should be golden brown on both sides, and cooked through. Remove and place on a plate (keep warm in a 200F degree oven).
Repeat until all batter is gone, adding 1/2 tablespoon of butter between each batch.