Preheat oven to 350 degrees F. Place oil in a large skillet over medium heat. When hot add chicken cubes and add dressing packet. Cook and stir for 5-7 minutes, until chicken is cooked through. Remove and set aside for a few minutes.
To prepare alfredo sauce, place butter and cream cheese into a large skillet over medium heat. Add heavy whipping cream and dressing packet. Stir until melted, whisk until smooth. Whisk in Parmesan cheese and stir until thickened, takes a few minutes. When sauce has thickened, remove from heat and set aside.
Cook spaghetti noodles according to package directions, drain and return back to pot over low heat. Pour in alfredo sauce and stir in chicken. Pour pasta into a 9 x 13 inch baking dish. Top with shredded Mozzarella cheese and bake for 30-35 minutes until slightly golden brown. Remove and garnish with chopped fresh parsley if desired. Cut into squares and serve.