Cook the lasagna noodles: Bring a large pot of salted water to a boil. Cook noodles according to the package instructions. Drain and rinse very well with cold water to prevent having the noodles stick together. Set aside.Preheat your oven to 350°F.
Make the cheese filling: In a large bowl, combine 2 cups mozzarella, ricotta, Parmesan, and your egg. Stir to combine.
Assemble the lasagna rolls: Lay the cooked lasagna noodles flat on a work surface. Spread about 1/4 cup of the cheese filling onto the top of the noodle. Spread a small strip of marinara sauce down the center of the noodle (about 1 tablespoon). Roll lasagna up and repeat until all of the lasagna is used up.
Prepare a 9x13 inch baking dish by spreading about 1/2 a cup of marinara sauce onto the bottom. Arrange your filled and rolled lasagna noodles in the baking dish, and top with the remaining marinara sauce. Evenly sprinkle the remaining cup of mozzarella cheese on top.
Cover the baking dish with aluminum foil. Bake (covered) in the center of your preheated 350°F for 30 minutes. Uncover, and bake for an additional 10 to 15 minutes, or until the cheese is melted and lightly golden brown.