Swiss-Onion-Zucchini Bake
["1 large Spanish onion (3 c. sliced onion)", "3 c. thinly sliced zucchini", "1/4 c. butter", "2 eggs, beaten", "1/4 c. milk", "1 tsp. salt", "1/8 tsp. pepper", "1/2 tsp. dry mustard", "1 c. grated Swiss cheese or Cheddar"]
["Peel and thinly slice onion.", "Separate into rings.", "Saute onion and zucchini in butter until tender.", "Place in shallow 1 1/2-quart baking dish.", "Combine eggs, milk, salt, pepper, mustard and 1/2 of cheese.", "Pour over vegetables.", "Sprinkle with remaining cheese.", "Bake at 375\u00b0 for 20 minutes or until firm.", "Makes 6 servings."]
["onion", "zucchini", "butter", "eggs", "milk", "salt", "pepper", "dry mustard", "Swiss cheese"]