Season the chicken. Pat the chicken dry.
Rub with salt, pepper, Italian seasoning, and paprika. This helps lock in flavor and keeps the meat from tasting bland.
Layer in the crockpot. Add the onion and garlic to the bottom of the crockpot. Place the seasoned chicken on top.
Pour in the chicken broth.
Add the creamy elements later. Cover and cook on Low for 3–4 hours or on High for 2–2.5 hours, until the chicken is cooked through but still juicy. Avoid overcooking.
Stir in the dairy. Add the cream cheese, heavy cream, and Parmesan. Stir gently until the sauce becomes smooth and creamy.
If needed, cover and cook for another 10–15 minutes to melt fully.
Wilt the spinach. Add the spinach in batches, stirring until it softens and blends into the sauce. It will look like a lot at first, but it cooks down quickly.
Adjust and finish. Taste and adjust salt and pepper. Add a pinch of red pepper flakes for heat and a small squeeze of lemon juice for brightness if you like.
Serve. Spoon over cauliflower rice, zucchini noodles, roasted broccoli, or enjoy as is.
Garnish with parsley.