Preheat your oven to 325 degrees F (165 degrees C) and lightly grease a deep 9x13-inch baking dish.

Cut the zucchini lengthwise into thin slices. Lightly salt these slices and let them drain in a colander to remove excess moisture.

In a large skillet over medium-high heat, brown the ground beef with black pepper, stirring continuously for about 5 minutes. Add in the diced green bell pepper and onion, cooking until the beef is no longer pink.

Incorporate the tomato sauce, tomato paste, red wine, basil, and oregano into the meat mixture. If the sauce is too thick, add a little hot water. Bring the mixture to a boil, then reduce the heat and let it simmer for approximately 20 minutes, stirring occasionally.

In a separate bowl, mix together the ricotta cheese, egg, and parsley until well combined.

To assemble the lasagna, start by spreading half of the meat sauce on the bottom of the prepared pan. Layer half of the zucchini slices over the sauce, followed by half of the ricotta mixture. Next, add all of the spinach and then all of the sliced mushrooms. Sprinkle with half of the mozzarella cheese. Repeat the layers with the remaining meat sauce, zucchini slices, ricotta mixture, and mozzarella cheese.

Evenly distribute the grated Parmesan cheese on top and cover the dish with foil.

Bake in the preheated oven for 45 minutes. Then, remove the foil, increase the oven temperature to 350 degrees F (175 degrees C), and bake for an additional 15 minutes.

Allow the lasagna to rest for 5 minutes before serving to let it set.

Serve warm and enjoy!