• If you are using traditional dried lasagna noodles that must be boiled, first boil them to an al-dente texture and lay them out on tea towels to dry slightly before proceeding with the recipe as directed.

Prepare the sauce.

• In a large mixing bowl, place the tomato puree, tomato paste, marinara sauce and salt, and whisk to combine well. Set the tomato sauce aside.
• If you'd prefer a completely homemade sauce, please the recipe notes for instructions.

Prepare the meat.

• In a large skillet over medium heat, add the ground beef. Break up the meat, stir, and cook until browned, stirring occasionally.
• As it cooks, sprinkle the salt, pepper and Italian seasoning over the top, and mix to combine.
• Allow the beef to sit for about 5 minutes to absorb the rendered juice. Drain any remaining fat and set the meat aside.

Prepare the cheese mixture.

• In a medium mixing bowl, mix together the ricotta, 3 cups shredded mozzarella, 1 cup Parmesan, the egg, salt, and pepper until thoroughly combined. Set aside.
• Mix together the remaining 1 1/2 cups mozzarella and 1/4 cup Parmesan in a small bowl. Set aside for topping the lasagna.
• Preheat your oven to 350° F. Grease a 9-inch x 13-inch x 3-inch casserole dish.

Assemble the lasagna layers.

• Spread slightly more than 1 cup of tomato sauce in an even layer over the bottom of the prepared casserole dish.
• Cover with a layer of lasagna noodles, overlapping them just by a little bit.
• Add another 1 cup sauce, then 1/3 of the meat, followed by 1/3 of the cheese mixture. Break up the cheese mixture into small clumps and scatter it as evenly as possible across the dish.
• Add another layer of lasagna noodles and gently press down to compact the first layer. Follow with 1 cup of sauce, covering the noodles completely. Add another 1/3 of the total meat, another 1/3 of the total cheese mixture.
• Repeat with a third layer of noodles, gently pressing down each layer, and finish with a final cup of sauce, and the remaining meat and ricotta cheese mixture in the same manner as before.
• If you have enough for a third layer of lasagna noodles, top the mixture with them.
• Top with the remaining tomato sauce and reserved mozzarella and Parmesan cheeses. Be sure to cover the whole dish with these cheeses, especially around the perimeter. They will help hold the whole dish together and absorb any excess moisture.

Bake the lasagna

• Cover the dish completely with nonstick or greased aluminum foil.
• Place the dish in the center of the preheated oven and bake for 25 minutes.
• Increase the oven temperature to 375°F, uncover the dish and continue to bake until the edges are bubbling and the cheese has browned, another 10 to 15 minutes. For a very browned top, turn on your oven's broiler.
• Remove the lasagna from the oven and let the lasagna sit for 10-15 minutes before slicing with a serrated knife and serving.