Preheat the oven to 375°F (190°C).
Prepare the noodles: Boil the lasagna noodles for 4 minutes, then drain in a colander. Rinse under cold water to stop further cooking and set aside.
Make the meat sauce: In a large saucepan, combine the cooked sausage or ground beef with 1 1/2 jars of marinara sauce. Simmer for 5 minutes.
Prepare the cheese mixture: In a mixing bowl, combine the ricotta cheese, 3 1/2 cups of mozzarella, Parmigiano-Reggiano, and eggs.
Assemble the lasagna: Grease a lasagna pan or a 9×13-inch baking dish with cooking spray. Spread 3/4 cup of marinara sauce on the bottom. Layer 3-5 lasagna noodles over the sauce, slightly overlapping. Spread a layer of the cheese mixture on the noodles, followed by a layer of meat sauce.
Repeat layers: Continue layering noodles, cheese mixture, and meat sauce two more times. Finish by topping with the remaining marinara sauce and sprinkling the remaining mozzarella cheese on top.
Bake: Cover the dish with foil and bake for 30 minutes. Remove the foil and bake for an additional 10 minutes to brown the cheese.
Rest and serve: Let the lasagna rest for 10 minutes before slicing and serving.