In a double boiler mix together flour, sugar, milk, egg yolks and salt. Allow water in the bottom of the boiler to come to a simmer or slow boil stirring constantly. Continue to stir until mixture thickens like syrup. Cook 15 minutes longer. Cool to room temperature. Add vanilla and stir.
Serve hot or cold with a slice of Janie's pound cake or in a small cup with fruit and whip cream.