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Creamy Chicken and Leek Casserole with Parmesan

Creamy chicken and leek casserole is baked under a golden panko and Parmesan topping until the sauce bubbles and the chicken reaches 165°F. A gently simmered leek and cream sauce keeps the chicken tender in this comforting oven-baked dinner.
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Prep Time 20 minutes
Cook Time 53 minutes
Resting 10 minutes
Total Time 1 hour 23 minutes
Servings: 6 servings
Course: Dinner
Cuisine: American
Calories: 650
Ingredients Equipment Method Notes

Ingredients
  

For the casserole
  • 2 lb chicken breasts boneless, skinless, cut into 1-inch pieces
  • 1 tsp kosher salt
  • 0.5 tsp black pepper
  • 2 tbsp unsalted butter
  • 2 leeks large; white and light green parts only, halved lengthwise, rinsed well, and thinly sliced
  • 2 cloves garlic minced
  • 3 tbsp all-purpose flour
  • 1.5 cup low-sodium chicken broth
  • 1 cup heavy cream
  • 1 tsp Dijon mustard
  • 0.5 tsp dried thyme
For the topping
  • 0.5 cup panko breadcrumbs
  • 0.5 cup Parmesan cheese finely grated
  • 2 tbsp unsalted butter melted

Equipment

  • 1 large skillet
  • 1 9x13-inch baking dish

Method
 

Prepare the casserole
  1. Heat the oven to 375°F and grease a 9x13-inch baking dish.
  2. Season the chicken pieces with the salt and pepper.
  3. Melt the butter in a large skillet over medium heat, add the leeks, and cook for 6–8 minutes until softened; add the garlic and cook for 30 seconds.
  4. Sprinkle the flour over the leeks and stir for 1 minute, then gradually whisk in the broth, cream, Dijon, and thyme; bring to a gentle simmer and cook for 3–5 minutes until the sauce thickens slightly.
Make the topping
  1. Stir together the panko, Parmesan, and melted butter in a small bowl.
Assemble and bake
  1. Arrange the chicken in the prepared baking dish and pour the leek sauce over it, stirring gently to distribute the chicken and sauce evenly.
  2. Sprinkle the topping evenly over the casserole and bake uncovered for 35–45 minutes, until the sauce is bubbling, the topping is golden, and the chicken reaches 165°F in the center.
  3. Let the casserole rest for 10 minutes before serving.

Notes

For tender chicken, cut the pieces evenly and check that the center reaches 165°F. Refrigerate leftovers for 3–4 days; freezing is not recommended because the cream sauce may separate. For a gluten-free variation, use gluten-free flour and gluten-free panko.