Place whipping cream in top of a double boiler. Cook over boiling water 10 minutes, stirring constantly. Add flour, stirring with a wire whisk until smooth. Gradually add scalded milk, stirring until smooth. Stir in sugar, salt, and 1/2 teaspoon cinnamon. Cook over low heat 10 minutes, stirring frequently. Spoon into individual serving bowls, and sprinkle with additional cinnamon, if desired. Serve hot.