Pizza Spaghetti

Name: Pizza Spaghetti
Ingredients: Cooking spray; 1 pound dry spaghetti; 1/2 medium green bell pepper; 1/4 small red onion; 2 cremini mushrooms (optional); 2 1/2 ounces sliced pepperoni, plus more for topping; 2 (13- to 14-ounce) jars pizza sauce, divided; 4 large eggs, divided; 1/2 teaspoon freshly ground black pepper; 1/4 teaspoon kosher salt; 1/2 cup grated Parmesan cheese (about 2 ounces), divided; 1 1/2 cups ricotta cheese (12 ounces); 1 cup shredded low-moisture mozzarella cheese (4 ounces); 2 tablespoons sliced black olives