1 cup flour
2 tsps baking powder
1/8 tsp salt
1 tsp sugar
1 cup water
1/2 cup shortening
4 eggs
1 tsp vanilla

FILLING
1 egg, beaten
1 cup sugar
1/3 cup cornstarch
1/2 tsp salt
2 cups milk
1 tsp vanilla

Whisk together the flour, baking powder, salt and sugar; set aside. Combine water and shortening in a saucepan and bring to a boil. Add the dry ingredients all at once, stirring vigorously until well blended. Remove from heat and allow to cool slightly. Add the eggs one at a time, beating well after each addition. Stir in the vanilla. Place by rounded tablespoonsful 1" apart on greased cookie sheet. Bake at 425 degrees for 25 minutes or until golden brown.
Filling: Combine egg, sugar, cornstarch and salt in a saucepan. Add milk and cook over medium heat until thickened, stirring constantly. Remove from heat and allow to cool slightly; stir in vanilla. Chill filling until just before serving. To serve, slice top of cream puff and fill with filling. Sprinkle with powdered sugar or chocolate sauce if desired.