Add paste, salt, pepper, oregano and hot water. Simmer for 1 1/2 hours. Scim off grease.
2Cook noodles & drain.
3Pre-heat oven to 375 degrees and grease 9 x 13 pan.
Mix meat mixture and rotini together in pan and add remaining raw onion and pepperoni on top.
Cover entire mixture with cheese and layer more pepperoni over the cheese. Shake the Parmesan cheese over entire casserole.
Bake until cheese melted on top and cool to serve.
4You can add any toppings you desire besides pepperoni and onion. That is just my personal favorite. Make sure to skim the grease off the meat sauce as much as you can. I have tried draining the grease after the browning process, which does work well, however, I have found it more flavorful with the skimming instead.