French Onion Chicken Casserole

Ingredients

• 2 tablespoons unsalted butter
• 1.5 cups yellow onion
• 0.5 cups chopped celery
• 0.5 cups carrot
• 1 tablespoon garlic
• 2 teaspoons fresh thyme leaves
• 1 teaspoon kosher salt
• 1 teaspoon ground black pepper
• 1 , 10.5 ounce
• 0.25 cups white wine
• 1 cup sour cream
• 1 cup mayonnaise
• 1 teaspoon Dijon mustard
• 2 cups Gruyere cheese , shredded, divided
• 6 cups chopped rotisserie chicken (
• 1 , 5 ounce

Instructions

1. 1

   Gather all ingredients. Preheat the oven to 350 degrees F (175 degrees C).

2. 2

   Melt butter in a large skillet over medium heat. Add onion, celery, carrot, garlic, thyme, salt, and pepper; cook, stirring often, until onions are softened and translucent, 5 to 7 minutes.

3. 3

   Add French onion soup and wine, and bring to a simmer over medium heat. Simmer, undisturbed, until reduced and slightly thickened, 2 to 3 minutes. Stir in sour cream, mayonnaise, and mustard, and return to a simmer. Add 1 cup Gruyère, and cook, stirring constantly, until completely melted and combined, about 1 minute. Remove from heat, and fold in chicken.

4. 4

   Transfer to a 9x13-inch baking dish. Sprinkle croutons evenly over chicken mixture; sprinkle evenly with remaining Gruyère cheese. Bake in the preheated oven until bubbling and cheese is melted, 12 to 15 minutes. Let rest 10 minutes before serving. Garnish with additional thyme and pepper.