Preheat oven to 350 degrees Fahrenheit. Grease a 9x13 baking dish.
Cook spaghetti as directed on package to al dente. Drain and rinse with cold water. Place in baking dish. I do not break the spaghetti in pieces.
Chop your onion and pepper.
Brown your sausage breaking it into small pieces as it cooks. Drain.
Whisk egg, milk, garlic powder, oregano and 1/4 cup Mozzarella together in a bowl. Pour over the spaghetti.
Pour pizza sauce over the spaghetti, gently mix to coat the spaghetti. You may need more or less sauce depending on your taste.
Add the peppers, onions, sausage, and pepperoni to top of spaghetti.
Sprinkle the remaining cheese on top.
Bake for 30 minutes until cheese is browned and bubbly and veggies are cooked.
Let stand for 5 minutes before cutting.
Serve this by itself or add garlic bread and salad.
