Place the chicken breasts in the bottom of a slow cooker in an even layer.
In a small bowl, stir together the melted butter, garlic, onion, Italian seasoning, salt, and black pepper. Pour the mixture evenly over the chicken.
Pour the chicken broth and heavy cream over the chicken. Cover and cook on LOW for 3½–4 hours or HIGH for 2–2½ hours, until the chicken is tender and fully cooked.
Remove the chicken from the slow cooker, shred it with two forks, then return it to the sauce and stir to combine.
Add the softened cream cheese and stir until completely melted and smooth.
Stir in the Parmesan cheese until fully incorporated.
Add the cooked and drained Banza pasta and gently stir until evenly coated in the sauce.
Sprinkle the mozzarella cheese evenly over the top. Cover and let sit for 5–10 minutes, until the cheese is melted.
Garnish with fresh parsley and serve warm.