Prepare the sauteed apples: In a large heavy skillet saute the apples in the butter over moderately high heat, stirring occasionally, for 5 minutes, or until they are softened, sprinkle them with the sugar and the cinnamon, and cook them over moderate heat, stirring occasionally, for 5 to 10 minutes, or until they are tender. Stir in the lemon juice and keep the mixture warm. Make the pancakes: In a bowl whisk together the egg yolks, the ricotta, the sugar, and the zest, add the flour, and stir the mixture until it is just combined. In a bowl with an electric mixer beat the egg whites with a pinch of salt until they hold stiff peaks, whisk about one fourth of them into the ricotta mixture, and fold in the remaining whites gently but thoroughly. Heat a griddle over moderately high heat until it is hot enough to make drops of water scatter over its surface and brush it with some of the melted butter. Working in batches, pour the batter onto the griddle by 1/4-cup measures and cook the pancakes for 1 to 2 minutes on each side, or until they are golden, brushing the griddle with some of the melted butter as necessary. Transfer the pancakes as they are cooked to a heatproof platter and keep them warm in a preheated 200°F. oven. Serve the pancakes with the sauteed apples and the maple syrup. Makes about twelve 3- to 4-inch pancakes. Gourmet September 1991