In a medium mixing bowl, stir together the cream of chicken soup, sour cream, milk, Parmesan cheese, onion, salt, pepper and paprika.
Stir in diced cooked chicken and spinach into sauce mixture.
Spray a 6 quart or larger oval slow cooker OR a 3.5 quart casserole slow cooker with non-stick cooking spray.
Place a layer of uncooked oven-ready lasagna noodles in the bottom of the slow cooker, breaking up the noodles as needed to make them fit and cover the bottom of the slow cooker as best as possible.
Spread one-third of the chicken/spinach sauce mixture over the layer of lasagna noodles.
Sprinkle a layer of shredded mozzarella cheese on top.
Repeat the layers two more time (noodles, chicken/spinach mixture, cheese).
Cover and cook on HIGH for 1 1/2 hours.
Switch slow cooker to LOW and continue to cook for 3 1/2 hours.
Turn slow cooker OFF and let lasagna sit and rest for 10 to 20 minutes to allow it to set up before serving.
Notes
This recipe uses cooked chicken breast. You can either use leftover chicken from a previous meal, rotisserie chicken from the grocery store or you can boil, bake or grill some chicken ahead of time.