1 can pieces and stems mushrooms
¾ cup chicken broth
1 tbls corn starch
1 tsp ground mustard
1 cup French onion rings
1 tbls butter.
In a small casserole dish combine all ingredients except onion rings. Stir, bake at 375 for 25 minutes. Sprinkle French onions on top and continue to bake until brown about 5 more minutes.