Preheat the oven to 400°F. Coat a 13- x 9-inch baking dish with nonstick cooking spray. Stir together the ricotta, spinach, egg, pesto, and salt in a medium bowl. Stir together the mozzarella cheese and Parmesan cheese in a separate medium bowl.
Spread about ½ cup of the marinara sauce in the bottom of the baking dish. Top with one-third of the frozen ravioli.
Top the ravioli with one-third of the ricotta mixture, one-third of the remaining marinara sauce, and one-third of the cheese. Repeat the layers two more times, ending with the cheese on top.
Coat one side of aluminum foil with nonstick cooking spray. Cover the baking dish with the aluminum foil, cooking spray side down. (This will help prevent the cheese from sticking to the foil.)
Bake for 20 minutes. Uncover and bake 25 to 30 more minutes or until the cheese is browned and the sauce is bubbly. Remove the lasagna from the oven and top with fresh basil leaves before serving, if desired.