Pre-heat the oven to 375℉.
In a large frying pan, fry the ground beef until no longer pink, then drain any fat.
Add the marinara sauce to the ground beef and the water (if using a jarred sauce add the water to the jar, cover and shake to get the remaining sauce in the jar). Let it simmer for 20 minutes.
Butter an 11 x 7 baking pan, and set aside.
In medium size bowl, combine the ricotta cheese, egg, and dried parsley. Stir until well blended.
Add a thin layer of the meat sauce onto the bottom of the buttered baking pan.
Take one lasagna noodle and liberally spread some of the ricotta mixture over it, then place it gently over the sauce in the baking pan. Repeat with the next two lasagna sheets, laying them down next to each other. It's ok if they do not lay flat.
Once the first layer is in the pan, top with some of the meat sauce, making sure the lasagna noodles are covered in some sauce.
Sprinkle a light layer of mozzarella cheese over the sauce.
Sprinkle a light layer of parmesan cheese over the mozzarella.
Repeat with the next layer of lasagna sheets by adding a layer of ricotta cheese, then topping with the sauce and mozzarella cheese.
Sprinkle the lasagna with black pepper.
Cover with aluminum foil and place the baking pan onto a baking sheet.
Bake until the sauce is bubbly and the pasta is cooked through 45-50 minutes.
Remove the aluminum foil and bake and additional 5-10 minutes to brown the top a bit.