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French Onion Chicken Orzo Casserole in a white baking dish with bubbly Gruyere, caramelized onions, and thyme on marble

Easy French Onion Chicken Orzo Casserole

Emily Wilson
This French Onion Chicken Orzo Casserole is a cozy one-pan dinner made with deeply caramelized onions, rotisserie chicken, tender orzo, savory broth, and a melty Gruyere topping. It tastes like classic French onion soup, but in creamy casserole form.
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Prep Time 15 minutes
Cook Time 55 minutes
Resting Time 10 minutes
Total Time 1 hour 10 minutes
Course Main Course
Cuisine American, French-inspired
Servings 6 servings
Calories 560 kcal

Equipment

  • 12-inch oven-safe skillet or 5 to 6 quart Dutch oven
  • Sharp knife and cutting board
  • Wooden spoon or spatula
  • Measuring cups and spoons
  • Cheese grater (optional)
  • Foil or oven-safe lid

Ingredients
  

Onion base

  • 2 tbsp Unsalted butter 28 g
  • 1 tbsp Olive oil 15 ml
  • 3 large Yellow onions, thinly sliced about 900 g total
  • 1 tsp Kosher salt 6 g, plus more to taste
  • 1 tsp Granulated sugar optional, helps browning
  • 3 cloves Garlic, minced

Casserole

  • 3 cups Rotisserie chicken (Rotisserie Kip), shredded about 400 g
  • 1 1/2 cups Orzo, dry 300 g
  • 3 cups Beef broth, low sodium 720 ml, or use chicken broth for a milder flavor
  • 3/4 cup Heavy cream 180 ml, or use half and half for a lighter option
  • 1 tsp Fresh thyme leaves or 1/2 tsp dried thyme
  • 1/2 tsp Black pepper

Cheese topping

  • 1 1/2 cups Gruyere cheese, shredded 150 g, Swiss is a good substitute
  • 1/3 cup Parmesan cheese, finely grated 30 g, optional but adds savory depth

Optional flavor boosters

  • 1 tsp Worcestershire sauce optional
  • 1 tsp Balsamic vinegar optional

Instructions
 

    1. Caramelize the onions: Heat butter and olive oil in a large oven-safe skillet over medium heat, then reduce to medium-low. Add onions, salt, and sugar (if using). Cook 30 to 40 minutes, stirring often, until deep golden and jammy. Stir in garlic for 1 minute.
    2. Build the base: Add beef broth and scrape the bottom of the pan. Simmer 2 minutes.
    3. Add orzo and cream: Stir in orzo, thyme, pepper, and Worcestershire (if using). Add cream and bring to a gentle simmer.
    4. Partially cook the orzo: Cover and cook on low for 8 to 10 minutes, stirring once or twice, until the orzo is mostly hydrated but still slightly firm. Add a splash more broth if it looks dry.
    5. Add chicken: Fold in shredded rotisserie chicken and keep stirring gentle so the pieces stay tender.
    6. Cheese and bake: Preheat oven to 375 F (190 C). Stir in 1 cup Gruyere. Top with remaining Gruyere and Parmesan. Bake uncovered 12 to 15 minutes, until bubbly and lightly browned.
    7. Rest and serve: Rest 5 to 10 minutes so the casserole thickens, then serve.

Notes

Tips: Cook the onions darker than you think for the best classic French onion soup flavor. Do not fully cook the orzo before baking or it can turn mushy. If leftovers thicken, reheat with a splash of broth.
Variations: For a Pollo Loco inspired version, add smoked paprika and a pinch of cayenne, then swap part of the Gruyere for pepper jack.
Nutrition Facts:
  • Calories: 560
  • Carbohydrates: 42 g
  • Protein: 34 g
  • Fat: 28 g
  • Saturated Fat: 14 g
  • Cholesterol: 110 mg
  • Sodium: 980 mg
  • Potassium: 620 mg
  • Fiber: 3 g
  • Sugar: 8 g
  • Vitamin A: 650 IU
  • Vitamin C: 12 mg
  • Calcium: 380 mg
  • Iron: 3.2 mg