In a large saucepan, boil water, butter, mustard, salt, and pepper.
Add flour all at once and stir until a smooth ball forms. Remove from heat; let stand for 5 minutes.
Add eggs, one at a time, beating well after each addition. Continue beating until mixture becomes smooth and shiny. Add parsley and green onions; mix well.
Drop by 2 tablespoonfuls 2 inches apart onto greased baking sheets. Bake at 400* for 18-20 minutes or until golden brown. Cut a slit in each to allow steam to escape; bake 5 minutes longer. Remove to wire rack to cool.