Line a 9-inch quiche dish or pie plate with pastry; trim excess pastry around edges. Prick bottom and sides of pastry with a fork. Bake at 400° for 3 minutes; remove from oven, and gently prick with a fork. Bake an additional 5 minutes. Let cool on a wire rack.
Combine whipping cream, eggs, salt, pepper, and nutmeg in a medium mixing bowl; mix well, and set aside.
Drain artichokes, reserving 2 tablespoons oil; set aside. Cut artichokes into bite-size pieces; set aside.
Sauté onion in reserved oil in a small skillet until tender; drain off oil. Stir in reserved artichoke pieces; spoon into prepared pastry. Pour whipping cream mixture over onion and artichokes; sprinkle cheese on top, and dot with butter. Bake at 375° for 45 minutes or until set. Let stand 10 minutes before cutting into wedges.