Add chicken breasts to the Crock Pot.
Pour in heavy cream, chicken broth, minced garlic, salt, pepper, and Italian seasoning.
Cover and cook on LOW for 3.5 to 4 hours (or until chicken is tender and fully cooked).
Remove the chicken and shred it using two forks.
Add uncooked fettuccine pasta to the slow cooker and stir gently.
Add shredded chicken back into the pot along with Parmesan cheese and butter.
Cover and cook on HIGH for an additional 20-30 minutes, or until pasta is fully cooked.
Stir everything well and garnish with chopped parsley before serving.