In a bowl, combine 2 cups of pureed squash with sage. Add salt and pepper to taste.
In another bowl, combine 15 ounce container of ricotta cheese with milk and parmesan (1/4 cup). Add salt and pepper to taste.
Coat the inside of a 5-6 quart slow cooker with non-stick spray. Place a layer of noodles at the bottom (you will have to break them to make them fit – don’t worry about using little pieces to fill in crevices, it will come out just fine). Cover with half of the squash mixture, spreading it evenly. Place another layer of noodles on top, then a layer of spinach and half of the ricotta mixture.
Repeat layers, ending with ricotta. Sprinkle mozzarella on top (1/4-1/2 cup). Cover and cook on low for 3-4 hours (until noodles are tender).