Preheat oven to 375°F (190°C).
In a large saucepan, heat olive oil over medium heat. Add chopped onion and minced garlic, cook until softened.
Add ground beef, cook until browned. Stir in marinara sauce, salt, and pepper. Simmer for 10 minutes.
Cook lasagna noodles according to package instructions. Drain and set aside.
In a mixing bowl, combine ricotta cheese and 1 cup of mozzarella cheese.
In a baking dish, spread a layer of meat sauce. Add a layer of noodles, then spread a layer of the ricotta mixture. Repeat layers, ending with a layer of meat sauce.
Sprinkle remaining mozzarella and Parmesan cheese on top.
Cover with foil and bake for 25 minutes. Remove foil and bake for an additional 25 minutes, until cheese is bubbly and golden.
Let lasagna rest for 10 minutes before serving.