This easy spinach lasagna recipe doesn't require pre-cooking the noodles, making prep a snap. It could be turned into a casserole if you substitute another kind of pasta for the noodles—ziti would work well.
Spray bottom and sides of a slow cooker with non-stick spray. Spread a few spoonfuls of sauce on the bottom of slow cooker to avoid noodles sticking.
Break uncooked lasagna noodles into pieces; place ⅓ of the broken lasagna noodles in a layer on bottom of the pot. Pour about ⅓ of the sauce evenly over the noodles. Next, place ½ of the ricotta and ⅓ of the mozzarella over the sauce. Place ½ of the spinach on top of the cheese. Place a few spoonfuls of sauce lightly over the spinach.
Repeat the layers starting with the broken noodles, then sauce, cheeses, spinach, and a little more sauce. Finally, layer the last ⅓ of the broken noodle pieces over the top. Cover noodles completely with remaining sauce. Sprinkle remaining mozzarella cheese over the top.
Pour water around the edges; cover and cook on low for 3 hours.