Coat crock pot with non-stick cooking spray. Spread 1 cup sauce on the bottom of the crock pot.
Boil pasta according to package directions, but only cook for 5 minutes. The pasta will finish cooking in the crock pot.
In a large skillet, crumble and cook sausage until it is browned on the outside. Add onion and mushrooms. Continue to cook until sausage is no longer pink in the middle.
Layer ingredients in the following order: 1/3 of sausage/onion/mushroom mixture, 1 cup sauce, 1/3 of cooked pasta, 1 cup cheese, 1/3 of pepperoni slices, 1/3 olives.
Repeat layers until ingredients are all used. On the 3rd layer, use 2 cups of cheese. This makes the top extra cheesy and it will look like the top of a pizza.
Place lid on crock pot and cook on low for 2-3 hours.
Oven Pizza Bake Option:
Layer ingredients in a deep dish pan or large casserole dish, omitting the last layer of cheese and pepperoni. Cover with foil and bake at 350 degrees for 30 minutes. Remove foil and sprinkle on the last layer of cheese and pepperoni. Bake for an additional 10-15 minutes, or until the cheese has melted.