In a large skillet cook onions, bell pepper and ground beef over medium heat until onions are translucent. Remove from heat and drain excess juices.

Layer pepperoni, sausages, ground meat mixture, mushrooms and Mozzarella cheese. Bake at 375 degrees for 25 minutes. Then raise temperature to 450 degrees and continue baking for 20 more minutes (until cheese begins to turn golden brown). Let sit 10 minutes before serving.