French Onion Soup Casserole

• servings: 6 servings
• total time: 1 hour 50 minutes

Ingredients

¼ cup unsalted butter

5 medium Vidalia onions, thinly sliced (about 3 lb.)

2 teaspoons kosher salt

½ teaspoon black pepper

3 thyme sprigs

2 flat-leaf parsley sprigs

2 bay leaves

1 (16-oz.) baguette, thinly sliced

⅓ cup all-purpose flour

3 cups reduced-sodium beef broth

½ cup sherry

8 ounces Gruyère cheese, shredded (about 2 cups)

1 teaspoon fresh thyme leaves

Directions

Cook onions: Melt butter in a Dutch oven over medium-low; add onions, salt, pepper, thyme and parsley sprigs, and bay leaves; cook, stirring often, until onions are golden brown, about 1 hour.

Toast baguette slices: Meanwhile, preheat oven to 350°F. Arrange baguette slices in a single layer on a baking sheet. Bake in preheated oven until lightly toasted, 12 minutes. Set aside.

Make sauce: Remove and discard thyme and parsley sprigs and bay leaves from onion mixture. Add flour, and cook, stirring constantly, 2 minutes. Add broth and sherry; bring to a boil over high. Boil, stirring constantly, until slightly thickened, 2 to 3 minutes.

Assemble casserole: Layer half of the toasted baguette slices in a 13- x 9-inch baking dish. Spoon onion mixture evenly over bread. Top evenly with remaining baguette slices. Sprinkle with cheese; cover with aluminum foil.

Bake casserole: Bake in preheated oven 30 minutes. Increase heat to broil. Remove foil; broil until cheese is bubbly, about 3 minutes. Sprinkle with thyme leaves.