Throughout France, you will find small restaurants, often tucked away on side streets, specializing in crêpes. In Brittany, the crêpes are made with buckwheat flour and the typical filling is a smear of salted butter, cheese, ham or bacon, thinly sliced fruit, and/or eggs. In most of France, crêpes are rolled up or folded into half or quarter circles, but in Brittany, where they are sometimes called galettes, they are folded differently. The filling is spread in the center of the pancake, the four rounded sides are folded in over the filling, forming a square, and then the crêpe is inverted onto a serving plate.

Make the crêpe batter: in a large bowl, stir together the buckwheat flour, all-purpose flour, and salt. in a small bowl, whisk the eggs until well blended; stir in the water and butter. Gradually whisk the egg mixture into the flour mixture until the batter is smooth. Cover and refrigerate for 1 hour. The batter should be the consistency of heavy cream. If it is too thick, whisk in additional water, 1 tablespoon at a time.

While the batter is resting, prepare the filling: in a large skillet, melt the butter over medium-low heat. Add the onions, increase the heat to medium, and cook, stirring, for 5 minutes. Add the apples and cook, stirring, for 10 to 15 minutes, until the apples begin to brown and have softened. Add the ham and sprinkle with the lemon juice, nutmeg and salt. Cover and set aside until ready to fill the crêpes.

Heat a 9- to 11-inch crepe pan over medium-low heat until hot enough for a drop of water to sizzle on contact. Brush the surface of the crepe pan with a thin film of the melted butter. Blot any excess with the tip of a paper towel. Stir the crêpe batter well with the whisk. ladle about ⅓ cup of the batter into the heated pan, and simultaneously tilt and roll the pan from side to side to coat the surface with a thin layer of batter. Cook for 1 minute, or until the edges begin to set. run the tip of a small, narrow rubber spatula under the edges of the crêpe to loosen it from the pan. Use your fingertips to lift the crêpe and quickly flip it over. Cook the other side for 30 seconds, or until the batter is set into a thin pancake. Do not brown the crêpe or cook it until crisp. Transfer the crêpe to a large, round plate. repeat with the remaining batter, brushing the pan with more butter if necessary. Stack the crêpes as they are made. You should have 12 crêpes. if making ahead, wrap the crêpes in plastic wrap or aluminum foil to prevent drying out. The crêpes can be refrigerated for up to 2 days.

If the crêpes have been made ahead, fill them one at a time by first warming each crepe in the pan over low heat. While they are still in the pan, sprinkle about ¼ cup of the cheese in the center of the crêpe. Top the cheese with a large spoonful of the warm apple filling, spreading it into a single layer. Fold in two opposite sides of the circle to cover the filling. Then fold in the remaining two rounded sides, overlapping slightly, to form a square envelope. With a wide spatula, lift the crêpe from the pan and invert it, so it is seam side down, onto a serving plate. Cover with aluminum foil to keep warm if not serving at once. Fill the remaining crêpes in the same way. reserve the remaining filling.

Just before serving, brush the smooth top of each crêpe with a thin film of the softened butter. reheat the remaining apple filling and spoon a portion on top of each crêpe. Serve at once.