Combine sour cream and milk and mix well. Pour into a shallow dish in which the chicken can be dipped.
In a second shallow dish, combine the bread crumbs, Parmesan cheese, rosemary, and sage.
Coat the chicken with the sour cream mixture and then dredge in the bread crumb mixture until well coated.
Place on a greased baking dish.
Bake for 25 minutes, or until tender and chicken is cooked through.
Meanwhile, prepare the spaghetti per the package directions.
Warm each sauce separately in small pots over the stovetop.
To serve, divide the pasta evenly between four plates. Top the pasta with tomato sauce, and place a piece of chicken on top. Drizzle with Alfredo sauce and sprinkle with the shredded cheese. Garnish with optional parsley.