Mix cornstarch, salt and sugar in top of double boiler to a thin, smooth paste with 2 cups of the milk.
Cook over boiling water for 20 minutes, with occasional stirring.
Beat eggs until light, gradually stir in a small amount of the hot cornstarch mixture, and return to the double boiler to cook 2 minutes longer with constant stirring.
Cool, pour through strainer, stir in rest of milk, cream and vanilla.
Pour into freezer can and freeze according to directions.