In the bottom of slow cooker, place chicken breasts. Add Cream of Chicken soup, onion, garlic and Italian seasoning.
Add chicken broth and cream cheese. Slice butter and place on top. Cover and cook on high for 4 hours or low for 6 hours.
When cooked, remove chicken and shred with 2 forks. If cream cheese is still lumpy, stir sauce with a whisk to incorporate. Add shredded chicken back into the sauce and stir.
Add parmesan cheese and mix well. Cover and let cheese melt for 5 minutes. Cook noodles and serve immediately topped with sauce.
Garnish with parsley (optional).