Heavenly Onion Casserole

Total Time

Prep: 15 min. + chilling Bake: 45 min.


6-8 servings

Updated: Oct. 03, 2022
I like to serve this side often. It goes wonderfully with many different main dishes including chicken, beef, lamb or pork.—Maryln Rose, Naples, Florida


  • 2 tablespoons butter
  • 3 medium sweet Spanish onions, sliced
  • 8 ounces fresh mushrooms, sliced
  • 1 cup shredded Swiss cheese
  • 1 can (10-3/4 ounces) condensed cream of mushroom soup, undiluted
  • 1 can (5 ounces) evaporated milk
  • 2 teaspoons soy sauce
  • 6 to 8 slices French bread (1/2 inch thick)
  • 6 to 8 thin slices Swiss cheese (about 4 ounces)


  1. In a large skillet, melt butter over medium-high heat. Saute onions and mushrooms until tender. Place in a 11x7-in. baking dish or 2-qt. baking dish. Sprinkle shredded cheese on top. Combine the soup, milk and soy sauce; pour over cheese. Top with bread and cheese slices. Cover and refrigerate 4 hours or overnight.
  2. Remove from the refrigerator 30 minutes before baking. Loosely cover with foil and bake at 375° for 30 minutes. Uncover and bake 15-20 minutes longer or until heated through. Let stand for 5 minutes before serving.