In a small bowl, beat together the egg, ricotta and parsley. Set aside.
In the Dutch oven, over medium-high heat, brown the beef and sausage. Drain the meat reserving 2 tablespoons fat (add 2 tablespoons olive oil, if there isn’t enough reserved fat). Transfer the drained meat to a large, heatproof bowl and set aside.
In the same pot, sauté the diced onion until it becomes translucent. Add the minced garlic and cook for an additional 30 seconds. Add red wine, red pepper flakes and the marinara sauce and cook an additional 5 minutes. Transfer the marinara mixture to the bowl with the meat and mix to combine.
With the Dutch oven over low-medium heat, ladle 2 cups of the marinara meat mixture into the bottom of the pot and cover the sauce with a layer of lasagna noodles (breaking the noodles to fit). Then, ladle the noodles with a layer of the marinara meat mixture.
Place spoonfuls of the ricotta/egg mixture over the marinara mixture and then add some mozzarella and grated Parmesan. Repeat the layers three more times (except there will be only three layers with the ricotta mixture).
The lasagna should be layered like this from the bottom layer to the top layer:
Marinara meat sauce, noodles, marinara meat sauce, ricotta mixture, mozzarella, Parmesan, noodles, marinara, ricotta, mozzarella, Parmesan, noodles, marinara, ricotta, mozzarella, noodles, marinara, mozzarella and finish with Parmesan.
Switch heat to low and cook, covered, 30-40 minutes or until the noodles are cooked through, and the lasagna is hot & bubbly. When the lasagna is cooked through and noodles have softened, it can be placed under the broiler for a few minutes to brown the cheese.
After removing the lasagna from the heat, garnish it with fresh basil and let it rest 10-15 minutes before serving.