Brown beef, then drain and set aside. Repeat with sausage, breaking it into bite-size pieces.
Mix sauce, dry pasta, and oregano together until pasta is well coated.
Spray the inside of a large crock pot with cooking spray. Alternate layers of each ingredient, using half of each at a time. (So, you will end up with two layers of each.) Layer in this order: pasta, beef, sausage, onions, peppers, mushrooms, cheese.
Top pepperoni then sprinkle with more oregano. Cook on low for apx 6 hours.