Preheat a griddle or large skillet on medium heat. Prepare the wet ingredients by mixing the ricotta, milk and egg yolks in a large bowl until combined. Add the optional vanilla extract and lemon zest, if desired. In a separate, smaller bowl, mix the dry ingredients: flour, sugar, baking powder, soda, salt and optional cinnamon, if desired. Slowly add in the dry ingredients to the wet, stirring constantly until all ingredients are fully incorporated. Do not over mix.