Put the butter in a saucepan and pour the water over it. As soon as water again reaches boiling point, add the flour all at once and stir until the mixture leaves the sides of the saucepan. Remove from heat and add unbeaten eggs, one at a time, beating mixture thoroughly between addition of eggs. Heat oil to 375 degrees F. Drop dough by teaspoonfuls and fry until well puffed and brown. Drain. Make an opening and fill the hollow inside with preserves. Sprinkle the top with confectioners' sugar.