French Onion Soup Casserole

Ingredients

• 4 tbsp unsalted butter
• 2 tbsp olive oil
• About 4 lbs yellow onions, thinly sliced
• 2 stalks celery, thinly sliced
• 2 bay leaves
• 4 sprigs fresh thyme, plus more leaves for garnish
• Kosher salt and freshly ground black pepper
• 2 tbsp all-purpose flour
• 4 cups low-sodium beef broth
• 1/2 cup dry white wine
• 1 baguette, cut into 1/2-inch slices
• About 1 lb Gruyere, grated (roughly 4 cups)

Directions

• Melt the butter and olive oil in a large Dutch oven or pot over medium heat. Add half the onions and celery with 1/2 tsp salt and a few grinds of pepper, then top with the remaining onions and celery, another 1/2 tsp salt, more pepper, the bay leaves and the thyme sprigs.
• Cook uncovered, stirring occasionally, until all the liquid has evaporated and the onions are very soft and deep golden brown, 45 minutes to 1 hour. Discard the bay leaves and thyme stems.
• Sprinkle in the flour and stir for about 1 minute, then pour in the beef broth and white wine. Simmer, stirring, until the liquid is thickened and mostly absorbed.
• Shingle and slightly overlap half the baguette slices in a 3-quart flameproof baking dish. Spread the onion mixture over in one layer, then shingle the remaining bread on top. Sprinkle the Gruyere over everything.
• Cover with foil and bake at 350F until hot and the cheese is melted, about 40 minutes. Remove the foil, switch the oven to broil, and broil until golden in spots. Sprinkle with fresh thyme leaves before serving.

Method reconstructed from the Food Network Kitchen recipe (check the source for exact amounts). From foodnetworkkitchen on Instagram; recipe at Food Network.