easy french onion soup casserole

French Onion Soup Casserole

  • Author: Kate Morgan Jackson
  • Prep Time: 15 minutes
  • Cook Time: 90 minutes
  • Total Time: 1 hour 45 minutes
  • Yield: 5 servings 1x
  • Category: Dinner
  • Method: Oven
  • Cuisine: French


  • ¼ cup butter
  • 3 sweet onions (Vidalia if you can get them!), peeled and sliced thin
  • 1 teaspoon salt
  • ½ teaspoon pepper
  • 1 tablespoon sugar
  • 1 medium sized loaf of French bread, cut into thin slices
  • Olive oil
  • ¼ cup flour
  • 2 cups beef broth
  • 1/3 cup sherry wine
  • 2 cups (about 8 ounces) shredded Swiss cheese
  • Fresh chopped parsley or thyme leaves for garnish


  1. Put in butter in a heavy deep saucepan over medium heat until melted. Stir in the onions, salt and pepper and reduce heat to medium low. Cook, stirring often, until the onions are tender and browned, adding in the sugar when they have cooked for 30 minutes, and then continuing to cook under they are nice and brown, about 45 minutes (this can be done ahead if you like!).
  2. While the onions are browning, preheat the over to 350 and arrange the bread slices on a cookie sheet. Brush with olive oil and then toast in the oven until lightly browned, about 15 minutes. Remove but leave the oven on.
  3. Sprinkle the flour over the onion mixture and stir until mixed in. Add the beef broth and the sherry, turn up the heat to medium high and simmer for a few minutes until the liquid starts to thicken up a little.
  4. Place a third of the bread slices in a 9×9 (or similar capacity) casserole. Ladle half the onion mixture over the bread and then top with another third of bread slices. Sprinkle with half the remaining cheese. Pour the remaining onion mixture over the bread slices and top with the rest of the bread slices. Cover the casserole tightly with foil and bake for 30 minutes.
  5. Remove the casserole, take off the foil and sprinkle the remaining Swiss cheese over the top. Return to the oven, turn the heat up to broil and toast until it is melted.
  6. Remove and sprinkle with chopped thyme or parsley and serve!