Mix 1½ cups of strong coffee with ½ cup of rich milk in a double boiler; add ½ cup of sugar, 1 tablespoonful of gelatin and a pinch of salt. Then stir in the yolks of 3 eggs beaten with ½ cup of sugar until it thickens. Remove from the fire; add the whites beaten to a froth and a teaspoonful of vanilla. Pack in a mold and freeze until hard and serve with whipped cream.