Fourth of July. Heat milk in a 3-quart saucepan over low heat until hot. Combine sugar, flour, and salt; gradually add sugar mixture to milk, stirring until blended. Cook over medium heat 15 minutes or until thickened, stirring constantly. 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-ha and vanilla in a large bowl; add chilled custard, stirring with a wire whisk. Pour into freezer can of a 1-gallon hand-turned or electric freezer. Freeze according to manufacturer's instructions. Let ripen 1-1/2 to 2 hours. Yield: 1 gallon.