To make the pancake batter, whisk together the eggs, milk, liqueur, and 2 tablespoons melted butter or vegetable oil. Add the flour slowly, whisking constantly to avoid lumps. Stir in the sugar and zests. Allow the batter to rest, refrigerated, at least 30 minutes before cooking.
Heat a nonstick 7-inch crepe or omelet pan over low heat until hot. Add 1 teaspoon melted butter, using either a brush or a tiny ladle, to coat the surface lightly. As soon as the butter has started to bubble, lift the pan off the heat and pour 2 tablespoonfuls pancake batter into the pan, tilting to spread the batter evenly across the bottom. Return the pan to the heat and cook on low until golden brown on the underside, then flip and brown the second side.
As each pancake is completed, remove it to an ovenproof platter set in a 200 degree F oven. If you fan the pancakes out on the platter, rather than stacking them directly on top of each other, they will be easier to separate later. Repeat until all the batter has been used. There should be enough batter to make at least 12 pancakes (2 for each serving).
Prepare the filling: Peel, core and cut the apples into 1/4-inch thick slices. In a saute pan, melt the butter, add the apple slices and saute over medium-high heat until they turn a rich golden color, about 6 to 8 minutes. Reduce the heat to low and carefully add the maple syrup, then the walnuts, cinnamon and lemon juice. Cook slowly until the apples are tender at the center of each slice, but not soft and mushy. When the liquid is reduced to a syrupy quality, remove the pan from the fire and add the Grand Marnier. Then return to the heat for a moment more to integrate the flavors. The filling can be made in advance and reheated just before finishing the dish.
To assemble the pancakes, place 3 tablespoons warm apple filling in the center of a pancake, and roll into a cigar shape. Place the filled pancakes back in the warm oven until all have been completed. Whip the heavy cream, confectioner's sugar and cinnamon together until soft peaks form. Fold in the creme fraiche. Serve 2 pancakes per person with a dollop of the cold cream and a drizzle of hot Fudge Sauce.
*Or substitute sour cream for the creme fraiche for a similar, if not identical, result.