1In a large saucepan, whisk flour and milk until smooth. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir in the potatoes, 1/3 cup cheese, salt and pepper. Cook over medium heat for 2-3 minutes.
2Remove from heat. Stir in sour cream and 1/4 cup onions. Cover; cook over medium heat for 10-12 minutes (do not boil). Garnish with remaining cheese, onions and bacon if desired.