Another variation of the make-ahead breakfast casserole that is sure to delight your family and/or guests. Sometimes for a variation, I also add 1/2 c chopped bell pepper and 1 cup sliced mushrooms when sauteeing the onions.
Toss together bread cubes, ham & cheese; place in greased 13 x 9 inch pan; set aside. Saute onion in butter; place in a bowl. Add eggs, milk & mustard; mix well & pour over bread mixture. Cover & refrigerate overnight. Remove from refrigerator a half-hour before baking. Bake uncovered at 350 degrees for 55-60 minutes or until set. Serve warm.