Preheat your oven to 375°F (190°C).
Cook the lasagna noodles according to package instructions; drain and set aside.
In a skillet, brown the ground beef or turkey over medium heat; drain excess fat.
Add marinara sauce to the skillet and stir to combine.
In a bowl, combine ricotta cheese, egg, Italian seasoning, salt, and pepper.
Spread a thin layer of the meat sauce on the bottom of a baking dish.
Layer three lasagna noodles over the sauce.
Spread half of the ricotta mixture over the noodles, followed by a third of the mozzarella.
Add another layer of meat sauce, followed by three more noodles, then the remaining ricotta and mozzarella.
Top with the final layer of noodles, remaining meat sauce, and sprinkle with Parmesan cheese.
Cover with foil and bake for 25 minutes, then remove the foil and bake for an additional 20 minutes until bubbly.
Let it rest for 10 minutes before slicing and serving.