Preheat oven to 350 F.
Cut eight slices of pepperoni into quarters, and set aside.
In an oven-proof skillet, brown sausage, onion and mushrooms until sausage is no longer pink. Stir in quartered pepperoni pieces. Drain excess fat.
In a bowl, mix pasta sauce, garlic powder, oregano leaves, pepper and salt. Fold in cooked spaghetti. In the same bowl, incorporate the sausage mixture into the sauce mixture.
In the same skillet, place half of the pasta-sausage mixture on the bottom, and spread 1 cup grated mozzarella cheese on top. Repeat layers. Place pepperoni slices on top, and sprinkle Parmesan cheese.
Bake skillet for 30 minutes or until sides are bubbly and Parmesan has been lightly toasted.
Remove from the oven. Allow the bake to sit for five minutes before serving.
Sue Hutchison was born and raised a block from the freeway in Southern California. She had an early start with industrial, large-scale cooking before age 20. She's always been both a beach bum and
at home in the kitchen, where she enjoys making new creations.