Place the chicken in a slow cooker that has been lightly greased with nonstick cooking spray. Season with salt and pepper to taste. Add the Italian seasoning, garlic powder, and onion powder. Pour the Alfredo sauce over top. Cover and cook on LOW for 4-6 hours or on HIGH for 2-3 hours, until the chicken is cooked through.
Shred the chicken with two forks and stir it into the sauce.
Cook the pasta in a large pot of well-salted boiling water according to package directions for al dente. Drain. Add the cooked pasta to the slow cooker with the chicken and sauce. Stir to combine. If the sauce seems too thick, add a splash of heavy cream, milk, or pasta cooking water to thin to the desired consistency.
Serve and garnish with Parmesan cheese, crushed red pepper flakes, additional ground black pepper, or fresh herbs.
