Season the potatoes: In a large bowl, toss chopped potatoes with olive oil, salt, pepper, garlic powder, and paprika until evenly coated. Spread them evenly in the bottom of your slow cooker.
Prepare the chicken: Season chicken breasts with salt, pepper, onion powder, paprika, Italian seasoning, and minced garlic. Place the chicken on top of the potatoes.
Add the sauce: Pour the garlic parmesan sauce evenly over the chicken and potatoes, making sure the chicken is fully coated.
Slow cook: Cover and cook on low for 4–6 hours or high for 2–3 hours, until chicken is cooked through and potatoes are tender.
Add cheese: About 10 minutes before serving, sprinkle mozzarella cheese over the top. Cover again until melted and bubbly.
Serve and enjoy: Garnish with fresh parsley if desired. Serve hot with a side of bread or salad.