1. In a covered jar, combine the milk, flour and salt. Shake well until fully dissolved.
2. Melt the butter in a 1-quart saucepan over low heat
3. Stir in the flour-milk mixture.
4. Cook over low heat, stirring constantly, until the mixture thickens and starts to bubble. Continue stirring until smooth and fully thickened.

This recipe makes 1 cup (equivalent to 1 can of cream soup) and can easily be doubled or tripled as needed.