Ingredients:

  • cups cooked, shredded or cubed Chicken Breast (about 450g)
  • Tablespoons Unsalted Butter (for leeks)
  • large Leeks (white/light green parts, thinly sliced and washed)
  • cloves Garlic (minced)
  • Tablespoons Unsalted Butter (for roux)
  • /4 cup All-Purpose Flour (30g)
  • cups Whole Milk (warmed slightly, approx. 475ml)
  • /2 cup Chicken Stock (low sodium, 120ml)
  • 1/2 cups English Cheddar Cheese (sharp, grated, plus 1/2 cup for topping)
  • teaspoon Dijon Mustard
  • Tablespoons Fresh Parsley (chopped)
  • Salt and Freshly Ground Black Pepper (to taste)
  • cup Panko Breadcrumbs (50g)
  • Tablespoons Melted Unsalted Butter (for topping)

Instructions:

  1. Preheat oven to 375°F (190°C). Lightly grease your 9x13 inch baking dish or oven-safe skillet.
  2. In a large skillet over medium heat, melt 3 Tbsp butter. Add sliced leeks and cook gently for 8–10 minutes until soft and sweet. Add garlic and cook for 1 minute more until fragrant. Set aside.
  3. In a medium saucepan, melt 4 Tbsp butter over medium heat. Whisk in the flour constantly for 2 minutes to create a roux.
  4. Slowly whisk in the warm milk until smooth. Continue whisking and bring to a simmer until the sauce thickens enough to coat the back of a spoon (about 3–5 minutes).
  5. Remove the sauce from the heat. Whisk in the chicken stock, Dijon mustard, salt, pepper, and 1 cup of the Cheddar cheese until fully incorporated. Stir in the fresh parsley.
  6. Gently fold the cooked chicken and the sautéed leeks into the cheese sauce. Taste and adjust seasoning. Transfer the mixture evenly into the prepared baking dish.
  7. Sprinkle the remaining 1/2 cup Cheddar evenly over the filling. In a small bowl, toss the Panko breadcrumbs with 2 Tbsp melted butter, then spread this buttery mixture evenly over the cheese layer.
  8. Bake for 35–40 minutes, or until the sauce is bubbling vigorously and the Panko topping is deeply golden brown and crunchy.
  9. Allow the casserole to rest for 10 minutes before slicing and serving.