I use jack cheese instead of or in combination with mozzarella because it is less rubbery. But any variations are good.
This works for an approximately 11 x 14 baking pan. If you have a larger or deeper pan, cook all the noodles in the package
1/2 - 3/4 package gently cooked lasagna noodles (estimate by layout before you start, how many you will need.)
1 package frozen spinach or large bunch cooked, salted fresh
1 pint container ricotta cheese
1 1⁄2 packages Monterey Jack cheese
1 1⁄2 cups grated Parmesan cheese (optional)
1 - 2 large jar Spaghetti Sauce (I like Emeril's Marinara)
Optionally: brown 1 lb. of lean ground beef with salt and Italian herbs. Add as a layer near the bottom.
Sauté spinach until melted and hot and evaporated mostly dry. Add a little butter during cooking to keep from sticking. Grate a little nutmeg into spinach to take away acidity, add chopped green onion.
Layer some sauce, then noodles, ricotta, spinach, cheese etc. Repeat.
Bake at 350º until hot and bubbly. About 30 minutes.