Recipe Details

Ingredients

• 1/4 cup unsalted butter

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

• 2 tsp. kosher salt

• 1/2 tsp. black pepper

• 3 thyme sprigs

• 2 flat-leaf parsley sprigs

• 2 bay leaves

• 1 (16-oz.) baguette, thinly sliced

• 1/3 cup all-purpose flour

• 3 cups reduced-sodium beef broth

• 1/2 cup sherry

• 8 oz. Gruyère cheese, shredded (about 2 cups)

• 1 tsp. fresh thyme leaves

Description

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.