Preheat oven to 400°. In a medium bowl, stir together ricotta, spinach, 1/2 cup Parmesan cheese, salt and pepper. Set aside. After noodles have been drained and béchamel sauce has been made, cover the bottom of a 13×9-inch baking dish with a thin coating of béchamel sauce. Add a layer of noodles. Cover with 1/3 of the ricotta mixture. Sprinkle on 1/3 of the mozzarella. Cover with some of the béchamel. Repeat layers twice saving enough béchamel to cover the top of the lasagna. On top of the last amount of mozzarella cheese, add another layer of noodles. Top with remaining béchamel and then sprinkle with some Parmesan. Cover with aluminum foil and bake for 40 minutes or until sides are bubbly. Uncover and cook for another 5-10 minutes. Allow to cool for 10-15 minutes before serving so lasagna can set up.