Preheat oven to 425°F (220°C).
In a saucepan, bring water, butter, and salt to a boil.
Add flour all at once and stir until a smooth ball forms.
Remove from heat and let stand for 5 minutes.
Add eggs one at a time, beating well after each addition.
Drop by tablespoonfuls 3 in. apart onto greased baking sheets.
Bake for 20-25 minutes or until golden brown. Remove to wire racks.
For filling, in a mixing bowl, beat cream until it begins to thicken. Add sugar and vanilla; beat until almost stiff.
Split puffs open; remove tops and set aside. Discard soft dough from inside. Fill the cream puffs just before serving.