Combine first 4 ingredients in a medium saucepan; bring to a boil. Add flour all at once, stirring vigorously over medium heat until mixture leaves sides of p an and forms a smooth ball. Remove mixture from heat, and cool slightly.
Add eggs, one at a time, beating well after each addition; beat until batter is smooth.
Spoon batter into a pastry bag with a 1/2-inch plain tip. Pipe batter into 2-inch mounds, 3 inches apart, onto greased baking sheets. Lightly brush each puff with egg white. Bake at 425° for 15 minutes or until puffed and golden brown. Remove to wire racks, and cool away from drafts.
Cut tops off cream puffs; remove and discard soft dough inside. Fill bottom halves with Chocolate Pastry Cream using a pastry bag, if desired. Replace top, and sprinkle with powdered sugar. Serve immediately.