In a saucepan, heat butter and water until almost boiling. Remove from heat. Add flour. Return to heat. Beat vigorously with a wooden spoon until mixture thickens, leaves sides of pan and forms a ball. Remove from heat. Add eggs, one at a time, beating constantly, until eggs are fully incorporated. Drop mixture by rounded tsp. Onto greased baking sheet, forming 12 large or 20 small puffs. Bake immediately at 400 F until light, puffy and golden, about 15 minutes for small puffs and 25 minutes for larger ones. Do not open oven door during baking time. Let cool, uncovered, on rack. Whip cream and fold into vanilla pudding. Cut off a lid on each puff. Fill with cream mixture. In a double boiler, melt chocolate and butter over low heat. Drizzle chocolate over puffs. Let cool. Serve.