Ingredients:

  • 12 ounces Spaghetti or Linguine
  • 3 cups Cooked Chicken Breast, shredded/diced
  • 2 tablespoons Unsalted Butter (for sautéing)
  • 2 small Shallots, finely minced
  • 8 ounces Cremini Mushrooms, sliced
  • 1/4 cup Dry Sherry or White Wine (optional)
  • 1 cup Frozen Peas, thawed
  • 4 tablespoons Unsalted Butter (for sauce)
  • 4 tablespoons All-Purpose Flour
  • 2 cups Chicken Stock (low sodium)
  • 1 cup Heavy Cream (or Double Cream)
  • 1/2 cup Grated Parmesan Cheese
  • 1 cup Shredded Gruyère Cheese
  • 2 tablespoons Fresh Parsley, chopped
  • Salt and Freshly Ground Black Pepper, to taste
  • 1/2 cup Panko Breadcrumbs
  • 2 tablespoons Melted Unsalted Butter (for topping)

Instructions:

  1. Prepare Pasta: Cook pasta until slightly under al dente (about 2 minutes shy of package instructions). Drain, reserving about 1 cup of the starchy cooking water. Set aside.
  2. Cook Aromatics & Mushrooms: In a large skillet, melt 2 tbsp butter. Sauté shallots until softened (about 3 minutes). Add mushrooms and cook until nicely browned and their liquid has evaporated. If using, deglaze the pan with sherry/wine, scraping up any tasty bits. Remove mushroom mix and set aside.
  3. Make the Roux: In a large saucepan, melt the 4 tbsp butter over medium heat. Whisk in the flour constantly for 2 minutes to cook out the raw flour taste. It should look like wet sand.
  4. Build the Béchamel: Gradually whisk in the cold chicken stock, ensuring no lumps form. Once smooth, bring to a gentle simmer, whisking frequently, until the sauce thickens enough to coat the back of a spoon.
  5. Finish the Mornay Sauce: Reduce heat to low. Stir in the heavy cream, Parmesan, and Gruyère until fully melted and smooth. Season aggressively with salt and pepper.
  6. Combine Filling: Gently fold the cooked chicken, mushroom mixture, thawed peas, and chopped parsley into the sauce. If the sauce seems too thick, add reserved pasta water a tablespoon at a time.
  7. Assemble: Toss the slightly undercooked pasta directly into the sauce mixture until every strand is coated. Transfer everything to a prepared 9x13 inch baking dish.
  8. Prepare Topping: In a small bowl, toss the Panko breadcrumbs with the 2 tbsp melted butter. Sprinkle evenly over the casserole.
  9. Bake: Bake in a preheated oven at 375°F (190°C) for 20–25 minutes, or until the sauce is bubbling and the topping is deep golden brown.
  10. Rest and Serve: Let the Chicken Tetrazzini rest for 10 minutes before serving to allow the sauce to set up.