Heat milk in a 3 quart saucepan over low heat until hot. Combine sugar, flour, and salt; gradually add sugar mix to milk, stirring until blended. Cook over medium heat 15 minutes or until thickened, stirring occasionally.
Gradually stir about one fourth of hot mixture into beaten eggs; add to remaining hot mixture, stirring constantly. Cook 1 minute; remove from heat, and let cool. Chill at least 2 hours.
Combine half and half and vanilla in a large bowl; add chilled custard, stirring with a wire whisk. Pour into freezer can of a 1 gallon ice cream freezer. Freeze according to manufacturer's directions. Let ripen in freezer, 1 1/2 to 2 hours.