French onion soup is the perfect fall meal to keep you and your family warm and toasty! But, dare we suggest that you take the comfort level up a notch by turning it into a casserole? This French Onion Soup Casserole combines two classic favorites in one — being packed with flavorful broth, creamy cheese, and topped with a toasted baguette — you'll have a fantastic fall favorite!
Ingredients• 1 (16-ounce) baguette, cut into 1/4 inch slices • 1/4 cup (4 tablespoons) unsalted butter • 2 large Vidalia onions, halved and cut from top-to-bottom into 1/4 inch slices • 3 large yellow onions, sliced • 1 teaspoon kosher salt • 1/2 teaspoon freshly ground black pepper • 5 fresh thyme sprigs, leaves removed, plus extra for topping • 1 bay leaf • 1/2 cup dry sherry • 1 cup unsalted beef broth • 2 cups unsalted chicken broth • 8 ounces (about 2 cups), shredded Gruyere cheese
Begin by setting your oven rack to the lower-middle position, then preheat your oven to 400 degrees F.
Grease a 9x13-inch baking dish with nonstick cooking spray. Set aside for the casserole.
Place the baguette slices onto a metal rack that's resting on a baking sheet. Bake for 8-10 minutes, until golden brown. Remove from the oven and set aside until ready to use.
While the bread slices bake, generously grease the inside of a large dutch oven with nonstick cooking spray and slice the onions (if you have not already done so).
Add the sliced onions, butter, black pepper, salt, bay leaf, and thyme to the dutch oven. Cover the dutch oven tightly, cooking the onions for 1 hour.
Remove the pot from the oven, then stir and scrape the bottom and sides of the pot. Place the pot back into the oven with the lid slightly off, continue cooking for an additional 1 hour.
Remove the pot from the oven once more, stirring and then scraping the bottom and the sides. The onions should be tender and slightly darker than golden-brown. If the onions have not yet reached the desired color, return the pot to the oven (with the lid slightly off) and cook for an additional 30 minutes.
Move the pot to the stovetop, turning the heat to medium-high (use caution as the pot is hot). Remove and discard the bay leaf from the onions.
Add in the sherry, chicken broth, and beef broth. Bring to a boil, stirring frequently for 4-5 minutes, until slightly thickened.
Layer half of the baked baguette slices into the previously prepared casserole dish.
Spoon the onion mixture evenly over the bread, then top with the remaining bread slices.
Drizzle the shredded cheese over top and cover with foil. Bake for 30 minutes at 400 degrees F.
Set the oven heat to broil, then remove the foil. Broil for 3 minutes, watching closely, until the cheese is nice and bubbly.
Garnish with extra thyme leaves, to your liking.