Preheat oven to 375 degrees F. Set a large pot of salted water over the stovetop and bring to a boil. Prepare the noodles according to the directions on the package. Drain the noodles and lay them out on clean tea towels.
In a large skillet, brown the Italian sausage over medium heat. Once cooked, add it to the marinara sauce.
Place the peppers, onion, mushrooms, and garlic in the skillet with the sausage drippings. Sauté lightly, for 3-4 minutes.
Mix the ricotta cheese, eggs, 1/4 cup of parsley, 1/2 cup parmesan cheese, 1/2 teaspoon salt, 1/4 teaspoon ground black pepper, and Italian seasoning together.
Spread 1/4 cup of sauce in the bottom of a 9x13-inch casserole dish. Cover with a single layer of noodles, then ricotta mixture, meat sauce, mozzarella cheese, vegetables (including olives), pepperoni, and repeat as many times as your pan will allow, usually 3-4 layers.
Sprinkle the top with mozzarella and parmesan cheese. Bake until the lasagna is bubbly around the edges, about 30 minutes. If the top starts to brown too much, tent with foil.