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Golden bubbly French Onion Chicken Orzo Casserole fresh from the oven in a cast iron skillet

French Onion Chicken Orzo Casserole

All the cozy, rich flavors of French onion soup transformed into a creamy, cheesy one-pan casserole with deeply caramelized onions, shredded chicken, orzo, and bubbly golden mozzarella.
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Prep Time 10 minutes
Cook Time 45 minutes
Total Time 55 minutes
Servings: 6 portions
Course: Dinner, Main Course
Cuisine: American, French-inspired
Calories: 500
Ingredients Equipment Method Notes

Ingredients
  

  • 2 tbsp unsalted butter
  • 1 tbsp olive oil
  • 2 large yellow onions thinly sliced, about 1/4-inch thick
  • 1 tsp sugar
  • 0.5 tsp salt
  • 3 cloves garlic minced
  • 1.5 cups orzo pasta about 10 oz dry
  • 2 cups cooked shredded chicken rotisserie works great
  • 0.5 tsp dried thyme
  • 0.25 tsp black pepper
  • 2 cups low-sodium chicken broth
  • 1 cup heavy cream or half and half for a lighter version
  • 1.5 cups shredded mozzarella cheese divided: 1 cup for sauce, 1/2 cup for topping
  • 0.5 cup grated Parmesan cheese freshly grated preferred
  • 0.5 tsp Worcestershire sauce optional, for umami boost

Equipment

  • Large 12-inch oven-safe skillet or Dutch oven
  • Lid or aluminum foil
  • Wooden spoon
  • Measuring cups and spoons

Method
 

  1. Preheat oven to 375 degrees F (190 degrees C). Melt butter and olive oil in a large oven-safe skillet or Dutch oven over medium heat until shimmering.
  2. Add sliced onions, sugar, and salt. Cook for 20 to 25 minutes, stirring every 3 to 4 minutes, until deeply caramelized and golden brown. They should reduce to about one-third their original volume. Stir in minced garlic during the last 1 to 2 minutes and cook until fragrant.
  3. Add orzo and stir for 2 minutes to lightly toast. Fold in shredded chicken, thyme, black pepper, and Worcestershire sauce if using.
  4. Pour in chicken broth and heavy cream. Bring to a gentle simmer, cover with a lid or foil, and cook on low heat for 8 to 10 minutes, stirring every 2 to 3 minutes, until orzo is tender with a slight bite. Add a splash of broth if the mixture thickens too quickly before orzo is done.
  5. Stir in 1 cup mozzarella and all the Parmesan until fully melted and creamy.
  6. Sprinkle remaining 1/2 cup mozzarella evenly over the top. Transfer to preheated oven and bake uncovered for 10 to 15 minutes until bubbly and golden brown.
  7. Remove from oven and let rest for 5 minutes before serving. Garnish with fresh thyme or parsley.

Notes

Do not rush caramelization; 20 to 25 minutes is essential for deep, sweet flavor. Stir orzo frequently while it cooks to prevent clumping. For a gluten-free version, substitute orzo with certified gluten-free orzo or cooked quinoa. Also verify your broth and Worcestershire sauce are gluten-free. Leftovers keep in the refrigerator for up to 3 days and reheat best with a splash of broth added.