Description
Hearty French onion soup meets comforting casserole in this delightful culinary fusion. Layers of caramelized onions, rich broth, and melted cheese create a soul-warming dish you’ll savor down to the last delicious bite.
Ingredients
Scale
Main Ingredients:
- 5 medium Vidalia onions, thinly sliced (about 1.36 kilograms or 3 pounds)
- 1 (16 ounces or 454 grams) baguette, thinly sliced
- 8 ounces (226 grams) Gruyère cheese, shredded (about 2 cups)
- 3 cups reduced-sodium beef broth
Seasoning and Herbs:
- 2 teaspoons kosher salt
- ½ teaspoon black pepper
- 3 thyme sprigs
- 2 flat-leaf parsley sprigs
- 2 bay leaves
- 1 teaspoon fresh thyme leaves
Fats and Liquids:
- ¼ cup unsalted butter
- ⅓ cup all-purpose flour
- ½ cup sherry
Instructions
- Caramelize the onions by melting butter in a Dutch oven over medium-low heat (about 60°F to 75°F). Incorporate whole onions, kosher salt, fresh ground black pepper, dried thyme, parsley sprigs, and bay leaves into the melted butter.
- Slowly cook the onion mixture for approximately 60 minutes, stirring every 10 minutes to ensure even browning and prevent burning. The onions should transform into a rich, golden-brown color with a deep, sweet flavor profile.
- Preheat the oven to 350°F (177°C). Slice the baguette into thin, uniform pieces and arrange them on a clean baking sheet in a single layer.
- Toast the baguette slices for 12 to 15 minutes until they become crisp and light golden, creating a crunchy base for the casserole.
- Remove the herb sprigs and bay leaves from the caramelized onions. Sprinkle all-purpose flour over the onions and cook for 2 minutes, stirring continuously to create a smooth roux.
- Gradually pour in beef broth and dry sherry, stirring constantly. Bring the mixture to a rolling boil and cook for 2 to 3 minutes until the sauce thickens and becomes glossy.
- Select a 13 x 9-inch (33 x 23 centimeters) baking dish and create the first layer using half of the toasted baguette slices, arranging them to cover the bottom completely.
- Carefully spoon the rich onion mixture over the first bread layer, ensuring even distribution. Top with the remaining baguette slices.
- Generously sprinkle grated Gruyère or Swiss cheese over the top layer, covering the entire surface.
- Cover the baking dish with aluminum foil and bake in the preheated oven for 25 to 30 minutes.
- Remove the foil and switch the oven to broil. Broil for 2 to 3 minutes until the cheese becomes bubbly and develops a golden-brown crust.
- Garnish with freshly chopped thyme leaves and serve immediately while hot and aromatic.
Notes
- Slow-caramelized onions transform this classic soup into a hearty, comforting casserole that captures deep, rich flavor profiles.
- Toasting baguette slices beforehand ensures a crispy texture that perfectly absorbs the luxurious onion broth.
- Layering bread and onion mixture creates delightful pockets of concentrated taste throughout the dish.
- Sherry adds unexpected depth and complexity, elevating the traditional onion soup experience.
- Broiling at the end helps develop a golden, crispy cheese crust that looks as amazing as it tastes.
- Fresh thyme leaves sprinkled on top provide a bright, herbal finish that cuts through the richness.
- Prep Time: 1 hour 20 minutes
- Cook Time: 45 minutes
- Category: Dinner, Appetizer
- Method: Baking
- Cuisine: French
Nutrition
- Serving Size: 6
- Calories: 550 kcal
- Sugar: 3g
- Sodium: 900mg
- Fat: 25g
- Saturated Fat: 15g
- Unsaturated Fat: 8g
- Trans Fat: 0g
- Carbohydrates: 65g
- Fiber: 4g
- Protein: 18g
- Cholesterol: 60mg