3 T Butter Or Margarine 3 ea Onions;Sliced In Small Rings 3 oz Emmenthaler Cheese; Grated 1 t Dry Mustard 2 c Spaetzle Noodles 2 T Chives; Chopped Heat butter in frypan, add onions, and brown lightly. Toss cheese with dry mustard. Add cooked noodles to cooked onions and cheese; mix well. Place mixture in an ovenproof casserole. Bake at 300 degrees F. for 20 to 30 minutes or until hot and bubbly. Sprinkle top with chopped chives before serving.