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French Onion Chicken Casserole

French Onion Chicken Casserole Recipe

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Prep Time 15 minutes
Cook Time 50 minutes
Total Time 1 hour 5 minutes
Servings: 6 servings
Calories: 472
Ingredients Method Notes

Ingredients
  

  • 2 tbsp unsalted butter
  • 1 tbsp olive oil
  • 4 large yellow onions, halved and thinly sliced
  • 1 tsp granulated sugar
  • 1 tsp kosher salt, plus more for chicken
  • 1/2 tsp black pepper
  • 2 garlic cloves, minced
  • 2 tbsp all-purpose flour
  • 1 1/2 cups beef broth
  • 1/4 cup dry sherry or white wine
  • 4 sprigs fresh thyme, plus leaves for garnish
  • 6 boneless, skinless chicken thighs (about 2 lbs)
  • 12 thin baguette slices (1/2 inch thick)
  • 6 oz Gruyère cheese, grated

Method
 

  1. Melt butter and oil in a large oven-safe skillet over medium heat. Add onions, sugar, salt, and pepper; cook, stirring often, for 25–30 minutes until deeply caramelized. Stir in garlic for the last 2 minutes, then transfer onions to a bowl.
  2. Season chicken thighs with salt and pepper. In the same pan over medium-high heat, sear until golden, about 3–4 minutes per side. Remove to a plate.
  3. Whisk flour into the pan drippings and cook 1 minute. Slowly pour in broth and sherry, scraping up browned bits. Add thyme sprigs, simmer 2–3 minutes until slightly thickened, then remove sprigs.
  4. Preheat oven to 375°F (190°C). Spread caramelized onions in the skillet, nestle chicken into the mixture, and top with baguette slices. Pour any chicken juices over the bread.
  5. Bake uncovered for 20–25 minutes until chicken reaches 165°F (74°C). Scatter Gruyère over the bread, switch oven to broil, and broil 2–3 minutes until cheese is bubbly and golden. Serve hot with fresh thyme leaves.

Notes

Let the casserole rest 5 minutes after the broiler so the broth settles; the bread will soften a bit, but that's part of its charm. If your skillet handles aren't oven-safe, wrap them in a double layer of foil first.