Preheat the oven to 375 F. Fill the bottom of a medium pot with about 1/2-inch of water and place over medium heat. Trim any excess stems off the spinach leaves, then spinach into the pot. Cover and simmer just until the spinach wilts. Strain the spinach, cool, squeeze out any excess water, and give it a rough chop. In a medium bowl, combine spinach, ricotta, basil, egg, parmesan, salt & pepper. In a 9 X 13-inch baking dish, spread a thin layer of pasta sauce. Unroll the fresh pasta sheets and trim two long slices to lay into the dish. Spread one-third of the ricotta mixture onto the pasta, then add another thin layer of sauce. Repeat for a total of three layers of pasta, three layers of ricotta, and four layers of sauce. Top with sliced mozzarella and bake for 35-45 minutes, or until top is golden brown and bubbly.