In a large skillet set over medium-high heat add the sausage and cooked until brown.

Remove sausage with a slotted spoon onto a paper towel-lined plate, set side.

In the same pan add in the onions, bell peppers and mushrooms. Cook until soft and golden in color, remove from heat and set aside.

Preheat oven to 350 degrees F and spray a small 9x13 jelly roll sized pan or casserole dish lightly with non-stick spray.

Spread an equal amount of marinara sauce on the bottom piece of each roll and place the bottom of the buns into your prepared pan.

Add 3 slices of pepperoni per bottom and top them all with 1/2 cup of mozzarella cheese, cooked sausage and cooked onions, peppers, mushrooms and the remaining shredded cheese.

Top the sandwiches with the tops of the buns.

In a small bowl whisk together olive oil, garlic powder, and oregano.

Brush the tops of buns with the mixture and sprinkle with 2 tablespoons of grated Parmesan.

Bake for about 20 minutes or until browned on the top and the cheese is melted in the sandwiches. Keep an eye on your sandwiches so the tops do not burn. If you notice them burning you can lightly cover them with foil they will still get warm in the middle and not burn the top.

Remove from the oven and top with remaining grated Parmesan cheese and minced parsley.