In top of double boiler melt 1-1/2 squares chocolate, add 1/2 cup sugar; mix well, add slowly 1 teaspoon gelatin soaked in 1 cup evaporated milk. Scald and stir until blended. Chill, add 1 cup water and freeze. Beat with egg beater once during the freezing. Serve with or without whipped cream, or with marshmallow sauce, flavored with 1/2 teaspoon vanilla.