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French Onion Soup Casserole Recipe
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French Onion Soup Casserole Recipe - Gourmet And Food

French onion soup casserole brings the classic French recipe into new territory, allowing for a range of flavors and textures. I’m excited to share my twist on this classic, which I’ve perfected over the years in my own kitchen. 
Through trial and some errors, I’ve mastered a combination that’s satisfying and memorable. My version celebrates simplicity while ensuring robust flavor and comfort. Plus, you can make it for any occasion.
Course Lunch
Cuisine French
Keyword French onion soup casserole recipe
Prep Time 10 minutes
Cook Time 1 hour
Total Time 1 hour 10 minutes
Servings 6
Calories 350kcal
Cost $

Ingredients

  • 5 medium Vidalia onions, thinly sliced about 3 lbs
  • 1/4 cup unsalted butter, softened
  • 2 teaspoons kosher salt
  • 1/2 tablespoon freshly ground black pepper
  • 3 sprigs of fresh thyme
  • 2 bay leaves
  • 2 sprigs flat-leaf parsley
  • 1 baguette, thinly sliced 16-ounce
  • 3 cups reduced-sodium beef broth, warmed
  • 1/2 cup dry sherry or white wine
  • 1/3 cup all-purpose flour
  • 8 ounces Gruyère cheese, shredded about 2 cups
  • 1 teaspoon Worcestershire sauce optional, for added depth
  • 1 teaspoon fresh thyme leaves, chopped
  • 1/2 teaspoon smoked paprika optional, for a subtle smoky flavor

Instructions

Step 1: Prepare the Onions

  • Start by melting the unsalted butter in a large saucepan over medium heat. Once melted, add your sliced onions. Sprinkle in the kosher salt and freshly ground black pepper. My secret here is to stir occasionally, allowing the onions to caramelize slowly for about 25-30 minutes, until they are beautifully golden brown.

Step 2: Add the Broth and Flour

  • Once your onions are perfectly caramelized, sprinkle the all-purpose flour over them and stir for about a minute. This will help thicken the sauce as it cooks. Gradually add in your warm beef broth, stirring continuously to avoid lumps. If you're using sherry or wine, add it in now. This step combines the sweetness of the onions with the depth of the broth.

Step 3: Season and Simmer

  • Throw in your fresh thyme, bay leaves, and parsley. Let this simmer for another 10 minutes. The goal is to let those flavors meld beautifully together. Remove the bay leaves, and adjust seasoning to taste. It's okay to tweak it until it’s just right.

Step 4: Assemble the Casserole

  • Preheat your oven to 375°F (190°C). In a baking dish, layer half of the baguette slices at the bottom. Pour half of your onion and broth mixture over the bread, then sprinkle with half of the Gruyère cheese. Repeat the layers, finishing with a heaping layer of cheese on top.

Step 5: Bake

  • Cover the baking dish with foil and bake for 20 minutes. Afterwards, remove the foil and bake for an additional 15 minutes, or until the top is bubbling and golden brown.

Step 6: Serve

  • Allow your casserole to cool slightly before serving. This dish is best enjoyed warm, and trust me, the aroma will draw everyone to the table.

Notes

  • Caramelization Takes Time: Give yourself enough time for the onions to caramelize fully. Rushing this step can leave you with less flavor.
  • Choose Quality Cheese: Go for a good quality Gruyère. It makes a world of difference.
  • Warm Broth is Key: Using warm broth helps integrate the flavors better and reduces cooking time.
  • Experiment: Don’t be afraid to play with additional herbs and spices for your own twist.
  • Make Ahead: You can prepare the casserole a day in advance. Store it in the fridge then bake when ready to serve.