1. Preheat oven to 375º. In a large pot of salted boiling water, cook pasta according to package directions until al dente, less 2 minutes. Drain and drizzle a bit of olive oil to prevent noodles from sticking together.
2. Meanwhile, in a large pot over medium-high heat, heat oil. Cook ground beef until no longer pink, breaking up with a wooden spoon, then drain fat. Return beef to skillet and add garlic and oregano and stir for 1 minute. Season with salt and pepper, then add marinara and stir until warmed through.
3. Combine ricotta, 1/4 cup Parmesan, and parsley in a large mixing bowl and season with salt and pepper. Set aside.
4. In a large casserole dish, spread a thin layer of meat sauce, a single layer of lasagna noodles, a layer of ricotta mixture, and a single layer of mozzarella, then repeat layers. Top last layer of noodles with meat sauce, Parmesan, and mozzarella.
5. Cover with foil and bake for 15 minutes, then increase temperature to 400º and bake uncovered for 18 to 20 minutes. Garnish with parsley and serve.
Credit : https://www.delish.com/cooking/recipe-ideas/recipes/a51337/classic-lasagna-recipe/