In a large skillet, heat on medium-high and begin breaking the ground Italian sausage into bite-size pieces. Cook until golden for 3-4 minutes. Push the sausage to the sides of the pot. In the middle of the pot, add in the uncured pepperoni, diced onion, garlic, and red bell pepper. Saute for 2 minutes, then add in the blended mushrooms. Mix well.
Next, add in the rotini pasta. Mix well, then pour in half the water, followed by all the pasta sauce. Use the remaining water and add to the pasta jar, close lid and shake. Then pour into the skillet. Mix well, then reduce heat to medium, and place a lid on the skillet. Cook for 15 minutes or until pasta is cooked to al dente. Stir periodically.
Once the pasta is done, turn the heat off, top with the fresh mozzarella cheese and place the lid back on for a few minutes until melted. *If your pan can handle the heat stick it under the broiler for a few minutes until the cheese is melted and golden in color.