Season the chicken breasts with salt, black pepper, garlic powder, onion powder, and Italian seasoning. Place the seasoned chicken in the slow cooker.
In a separate bowl, mix together the softened cream cheese, chicken broth, and heavy cream until smooth. Pour the mixture over the chicken in the slow cooker.
Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the chicken is cooked through and tender.
About 30 minutes before serving, shred the chicken in the slow cooker using two forks. Stir in the shredded cheddar cheese until melted and well combined.
Serve hot, garnished with chopped green onions.