Creamy One-Pot Chicken Tetrazzini Will Become a Family Favorite

Gather the ingredients. Preheat the oven to 425 F. Butter a 2 1/2- to 3-quart baking dish. The Spruce / Diana Rattray Break the spaghetti up into shorter lengths and cook in boiling salted water following the package directions. Drain and set aside. The Spruce / Diana Rattray Meanwhile, melt 1 tablespoon of butter in a large skillet or sauté pan over medium heat. Add the sliced mushrooms and cook, stirring, for about 5 minutes, or until tender. Remove the mushrooms to a plate with a slotted spoon and set aside. The Spruce / Diana Rattray Add 4 tablespoons of butter to the same pan and place it over medium heat. Add the flour and cook, stirring, for 2 minutes. Gradually whisk the cream and chicken stock into the flour mixture. Add the dry Sherry to taste, if using. Add about half of the Parmesan cheese and continue to cook, stirring, until the sauce thickens. Taste and add kosher salt, as needed. If the sauce is too thick, add extra cream or stock. The Spruce / Diana Rattray Add the mushrooms and cooked chicken to the sauce mixture and continue to cook until hot. Add chopped parsley, if using, and stir to blend. The Spruce / Diana Rattray Turn the drained spaghetti into the prepared baking dish. Pour the sauce mixture over the pasta and spread it to cover. Top the casserole with the remaining Parmesan cheese. The Spruce / Diana Rattray Bake the casserole in the preheated oven for 15 to 20 minutes, until hot, bubbly, and lightly browned. The Spruce / Diana Rattray Serve chicken tetrazzini with a salad or fresh vegetables and extra Parmesan cheese. The Spruce / Diana Rattray