Heat 2 tablespoons olive oil in a large pot over medium-high heat. Add the mushrooms, season with salt and pepper and cook, stirring, until lightly browned, about 5 minutes. Transfer to a plate using a slotted spoon. Add the sausage to the pot and cook, breaking up the meat, until no longer pink, about 3 minutes. Add the onion and bell pepper, season with salt and pepper and cook, scraping up the browned bits, until the vegetables soften, about 4 minutes. Add the marinara sauce, bring to a simmer and cook 5 minutes. Remove from the heat and stir in the cooked mushrooms, ham, olives and about 3/4 cup pepperoni; season with salt and pepper. Let cool slightly.
Meanwhile, preheat the oven to 375 degrees F. Brush an 8-inch round springform pan with olive oil and line with foil, leaving an overhang. Bring a pot of salted water to a boil. Add the noodles and cook as the label directs; drain and toss with the remaining 1 tablespoon olive oil.
Combine 2 cups mozzarella, the ricotta, parmesan and eggs in a bowl; season with 1/2 teaspoon salt and a few grinds of pepper.
Wrap some lasagna noodles around the inside of the pan, overlapping slightly and trimming as needed. Cover the bottom of the pan with more noodles, overlapping slightly and letting them extend up the side of the pan. Spread 2 cups sauce in the pan and top with half of the ricotta mixture; cover with a layer of noodles. Repeat with 2 more cups sauce, the remaining ricotta mixture and another layer of noodles, letting them extend up the side of the pan (you might not use all the noodles). Top with the remaining sauce, 1 cup mozzarella and 1/4 cup pepperoni.
Bake until browned and bubbling, about 1 hour (tent with foil if the top is browning too quickly). Let stand 30 minutes to 1 hour, then lift out of the pan using the foil. Remove the foil and slice.
Photograph by Jon Patterson