Preheat your oven to 375°F (190°C).

In a large skillet, cook the ground beef over medium-high heat until browned. Drain off any excess grease.

Add the diced onion and minced garlic to the skillet with the beef and cook until the onion is softened, about 5 minutes.

Stir in the marinara sauce and crumbled bacon. Simmer for 10 minutes to allow the flavors to meld.

In a medium bowl, combine the ricotta cheese, egg, 1/4 cup of the Parmesan cheese, oregano, and black pepper.

Spread a thin layer of the meat sauce on the bottom of your 9x13 inch baking dish.

Layer four cooked lasagna noodles over the sauce. Spread half of the ricotta cheese mixture over the noodles. Sprinkle with 1 cup of the mozzarella cheese.

Repeat the layers: meat sauce, noodles, the remaining ricotta mixture, and 1 more cup of mozzarella cheese.

Add the final layer of noodles, the remaining meat sauce, and top with the remaining 1 cup of mozzarella cheese and the remaining 1/4 cup of Parmesan cheese.

Cover the dish with foil and bake for 25 minutes. Remove the foil and bake for another 15-20 minutes, or until the cheese is bubbly and golden brown.

Let the lasagna rest for 10-15 minutes before slicing and serving. Garnish with fresh parsley.