Frank and Potato Bake

¼ cup finely chopped onion
1 tbsp. margarine or butter
1 tbsp. flour
½ tsp. Salt
2/3 cup milk
¾ cup shredded American cheese or process cheese spread
1 tbsp. snipped parsley
2 tsp. Prepared mustard
8 ounces frankfurters, sliced (4 or 5)
4 medium potatoes, cooked, peeled, and sliced
Snipped parsley (optional)

In small saucepan cook onion in margarine till tender but not brown.  Blend in flour and salt.  Add milk all at once; cook and stir over medium heat till thickened and bubbly.  Add shredded cheese, stirring to melt.
 Stir in 1 tablespoon snipped parsley and the mustard.  Fold in sliced frankfurters and potatoes; turn into a 1 - quart casserole.  Cover and bake in 350* oven about 35 minutes or till heated through.  Garnish with additional snipped parsley, if desired.  Serves 4.