This hearty, homey take on French onion soup celebrates Georgia-grown Vidalia onions, which typically come into season in late April. Naturally sweet Vidalias are perfect for caramelizing, and this indulgent casserole with layers of bread, onions, and cheese is a terrific way to enjoy them. We didn’t think French onion soup could get any more comforting, but we took the Southern route and made it into an even cozier casserole. This dish amplifies the richness of the classic soup you crave, and it’s ideal to serve as a hearty family dinner or pack up and bring to the church potluck. It takes time to slice and caramelize the onions, but you can do this step a day ahead and store the cooked onions in the refrigerator.
1/4 cup unsalted butter
5 medium Vidalia onions, thinly sliced (about 3 lb.)
2 teaspoons kosher salt
1/2 teaspoon 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 ounces Gruyère cheese, shredded (about 2 cups)
1 teaspoon fresh thyme leaves
How to Make It
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.
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.
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.
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 in preheated oven 30 minutes. Increase heat to broil. Remove foil; broil until cheese is bubbly, about 3 minutes. Sprinkle with thyme leaves.