Preheat the oven to 350*. Lightly spray a 9x13 baking dish with nonstick spray and set aside.
Cook and drain the linguine according to the package instructions and set aside.
In a large mixing bowl, whisk together the cream of chicken soup, cream of mushroom soup, chicken broth, heavy cream, whole milk, sour cream, onion powder, kosher salt and black pepper. Whisk until all the ingredients are completely smooth.
Using tongs, add the linguine to the creamy soup mixture and “toss” the noodles in the sauce until coated.
Add the diced chicken breast and “toss” until complete incorporated and coated.
Pour the coated noodles and chicken into the prepared baking dish. Evenly sprinkle the shredded cheese over the noodles and chicken. Bake uncovered for 40 minutes.
Evenly sprinkle the chicken tetrazzini with the fresh chopped parsley.
STORAGE: Any leftovers should be stored covered in the refrigerator for 3-4 days. This dish can be frozen for up to 4-6 months.