Heat water, fat, and salt to boiling. Simmer until fat has melted. Reduce heat as much as possible without eliminating it altogether. Add flour all a once. Stir briskly until mixture forms a ball that no longer leaves the sid of the saucepan, but no longer. Remove from heat. Add eggs one at a time, beating after each addition until mixture is stiff and glossy. Drop by spoonful into deep, hot fat (370) and cook until delicately brown. As soon as they are cooked enough on one side, they will turn themselves over. Remove when browned on both sides. Drain and sprinkle lightly with powdered sugar. If desired, cut a split in each and stuff with marmalade or chocolate filling.