Ingredients:

  • 3 Tbsp Unsalted Butter (for filling base)
  • 2 large Leeks (white/light green parts only), thinly sliced
  • 3 cloves Garlic, minced finely
  • 3 Tbsp All-Purpose Flour
  • 1 ½ cups warm Chicken Stock (low sodium)
  • 1 cup Heavy Cream (35% fat)
  • 3 cups Cooked, Shredded Chicken
  • 1 cup Frozen Peas
  • 1 cup (packed) Gruyère Cheese, grated
  • 1 tsp Fresh Thyme Leaves
  • Salt and Freshly Ground Black Pepper, to taste
  • 1 ½ cups Panko Breadcrumbs (for topping)
  • ½ cup Parmesan Cheese, freshly grated (for topping)
  • 3 Tbsp Melted Unsalted Butter (for topping)
  • 2 Tbsp Fresh Parsley, chopped (for topping)

Instructions:

  1. Preheat oven to 400°F (200°C). Lightly butter a 9x13 inch baking dish.
  2. Melt 3 Tbsp of butter in a large, deep skillet or Dutch oven over medium heat. Add sliced leeks; cook gently for 8-10 minutes until very soft (sweated) but not browned. Add minced garlic and cook for 1 minute more.
  3. Sprinkle flour over the leeks and stir constantly for 1 minute to cook out the raw flour taste.
  4. Gradually whisk in the warm chicken stock until smooth. Bring to a gentle simmer, stirring constantly until the sauce thickens enough to coat the back of a spoon (about 3-5 minutes).
  5. Remove the skillet from the heat. Stir in the heavy cream, shredded chicken, frozen peas, grated Gruyère, and thyme. Season aggressively with salt and pepper. Taste and adjust seasoning.
  6. Pour the mixture evenly into the prepared baking dish.
  7. In a small bowl, combine Panko breadcrumbs, grated Parmesan, melted butter, and fresh parsley until the crumbs are evenly coated.
  8. Sprinkle the crumb mixture evenly over the casserole filling. Bake for 30–35 minutes, or until the filling is bubbling vigorously and the topping is deep golden brown and crisp.
  9. Let the casserole rest for 10 minutes before slicing and serving to allow the sauce to set.