Cook the pasta as directed on package but stop 3 minutes early, drain and set aside.
In a large saucepan, cook the sausage over medium heat for about 10 minutes.
Mix sauce with the sausage and 3/4's of the olives and pepperoni, then set aside.
Mix ricotta, mozzarella, and parmesan and set aside.
Layer half the pasta, half the sauce, and half the cheese mixture in a large baking dish. Repeat the layers and top with remaining olives, pepperoni, and oregano.
Cover with foil and bake in a preheated 350F/180C oven until bubbling, about 20-30 minutes. Remove foil and bake until cheese is melted and golden brown, about 10 minutes.