Lightly spray the inside of a 6-quart slow cooker with nonstick cooking spray.
Place the chicken in the bottom of the crockpot.
In a bowl, whisk together the golden mushroom soup, chicken broth, Italian seasoning packet, black pepper, and garlic (if using).
Pour the sauce mixture over the chicken.
Scatter the butter pieces on top.
Cover and cook on LOW for 4½ to 5½ hours, until the chicken is cooked through and tender.
About 20–30 minutes before serving, add the cubed cream cheese. Cover again and let it soften.
Stir or whisk the sauce until smooth and creamy.
Shred the chicken with two forks (or slice into chunks), then stir it back into the sauce.
Cook the angel hair pasta according to package directions until al dente. Drain.
Serve the chicken and sauce over pasta. Top with Parmesan and parsley if desired.