Dice the chicken into bite-sized pieces and prepare the other ingredients.
Layer the chicken, garlic, onion, and Italian seasoning in the crock pot. Pour chicken broth over the top.
Add cream cheese in chunks but do not stir. Cook on low for 4-6 hours (or high for 2-3 hours).
Cook pasta separately about 30 minutes before the crock pot finishes. Reserve ½ cup pasta water.
Stir the cream cheese mixture in the crock pot to form a smooth sauce. Shred the chicken.
Combine the cooked pasta with the creamy chicken sauce, adjusting consistency with pasta water or broth if needed.
Garnish with Parmesan cheese and parsley. Serve warm.