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French Onion Chicken Orzo Casserole

French onion chicken orzo casserole with deeply caramelized onions, tender orzo, and gooey melted Gruyère and mozzarella. Baked until the cheese is golden and bubbling and the chicken reaches 165°F (74°C).
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Prep Time 20 minutes
Cook Time 1 hour 10 minutes
resting 10 minutes
Total Time 1 hour 40 minutes
Servings: 8 servings
Course: Dinner
Cuisine: French
Calories: 680
Ingredients Equipment Method Notes

Ingredients
  

Chicken
  • 2 lb boneless, skinless chicken breasts
  • 2 tbsp olive oil
  • 1 tsp garlic powder
  • 1 tsp onion powder
  • 1 tsp dried thyme
  • 1 tsp kosher salt
  • 0.5 tsp black pepper
Casserole
  • 2 large yellow onions
  • 3 tbsp unsalted butter
  • 3 garlic
  • 1.5 cup uncooked orzo pasta
  • 3 cup low-sodium beef broth
  • 0.5 cup heavy cream
  • 1 tbsp Worcestershire sauce
  • 1 tsp Dijon mustard
  • 1 tsp fresh thyme leaves
  • 1.5 cup shredded Gruyère cheese
  • 1 cup shredded mozzarella cheese
  • 0.5 cup grated Parmesan cheese
Garnish
  • 1 fresh thyme sprigs
  • 1 chopped fresh parsley

Equipment

  • 1 cast iron skillet
  • 1 sheet pan

Method
 

Prepare the oven
  1. Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
Caramelize the onions
  1. Melt the unsalted butter in a large skillet over medium-low heat. Add the large yellow onions and cook for 25–30 minutes, stirring frequently, until deeply golden and caramelized.
  2. Add the garlic during the final minute. Stir until fragrant, then turn off the heat.
Cook the chicken
  1. Season the boneless, skinless chicken breasts with garlic powder, onion powder, dried thyme, kosher salt, and black pepper. Coat evenly.
  2. Heat the olive oil in another skillet over medium-high heat. Sear the chicken for 5–6 minutes, until lightly browned and not fully cooked.
Build the casserole
  1. Add the uncooked orzo pasta, low-sodium beef broth, heavy cream, Worcestershire sauce, Dijon mustard, and fresh thyme leaves to the caramelized onions. Stir well to combine.
  2. Fold in the browned chicken and half of the shredded Gruyère cheese. Mix until the orzo is evenly coated.
Assemble and bake
  1. Transfer everything to the prepared baking dish. Sprinkle the remaining shredded Gruyère, shredded mozzarella cheese, and grated Parmesan cheese evenly over the top.
  2. Cover with foil and bake for 30 minutes at 375°F (190°C). The mixture should be bubbling around the edges.
  3. Remove the foil and bake for another 10–15 minutes at 375°F (190°C). Bake until the orzo is tender, the chicken reaches 165°F (74°C), and the cheese is golden and bubbling.
Serve
  1. Let the casserole rest for 10 minutes. This helps it set so the orzo stays tender, not soupy.
  2. Garnish with fresh thyme sprigs and chopped fresh parsley before serving. Serve warm.

Notes

For the most French onion flavor, keep the onions at medium-low and stir often so they caramelize instead of browning too quickly. Store leftovers in an airtight container in the refrigerator for up to 3 days; reheat in the oven or microwave until hot throughout. Freezing is not recommended because orzo and cream can soften and change texture. If you want a lighter option, use half-and-half instead of heavy cream and reduce the total cheese slightly for a lower-fat result.