In a large skillet over medium heat, add your ground beef or Italian sausage along with the diced onion. Cook until the meat is browned and the onion becomes translucent, about 5-7 minutes, stirring occasionally.

Once the meat is browned, add the minced garlic and sauté for 1 minute until fragrant. Pour in the marinara sauce along with the Italian seasoning, stirring to combine. Let the mixture simmer for 10 minutes on low heat.

In a mixing bowl, combine the ricotta cheese, egg, half of the grated parmesan, and a sprinkle of salt and pepper. Mix until smooth and creamy.

Preheat your oven to 375°F (190°C). In a 9x13 inch baking dish, start by spreading a layer of the meat sauce on the bottom. Layer the no-boil lasagna noodles, followed by half of the ricotta mixture, and then sprinkle with mozzarella cheese. Repeat this layering process, finishing with a layer of meat sauce topped with the remaining mozzarella.

Cover the baking dish tightly with aluminum foil. Bake in the preheated oven for 25 minutes, then remove the foil and continue baking for another 20-25 minutes.

Once out of the oven, let the No Boil Lasagna rest for 10-15 minutes before slicing.