Place chicken breast into slow cooker. Season with dry Italian dressing mix. In a separate bowl, whisk together softened cream cheese, butter, cream of chicken, chicken broth, and garlic powder.
Whisk well. Some chunks of cream cheese will remain and that's okay. Pour mixture on top of chicken and heat on low for 3-4 hours or until easy enough to shred with 2 forks.
When ready to serve, shred chicken with 2 forks and add cooked pasta (boiled seperately on stovetop) to the sauce, use tongs to incorporate. Serve topped with shredded parmesan cheese.