Of course adjust measurements for your size SC. Mine is a big one and this made 6 decent sized servings.
Soften onion, spinach and leek in a saucepan with some oil and garlic.
Once softened, thoroughly mix all ingredients in a big bowl. Salt and pepper to taste. Line SC lightly with some oil or butter (I used butter) and put some sauce to cover the bottom. Then do layers. One layer lasagne, ricotta mix, grated cheese, one layer lasagne, one layer ricotta mix, one layer sauce. Then repeat until done. Top with sauce and some cheese.
I put on low for about 3 hours but do it to suit your SC. I added some water just around the edges about half way through and lifted the sides to keep them moist. Serve with salad. I'm serving with rocket, tomato, lettuce, onion and cheese salad. (Chips if you're feeling naughty)