Pizza Pork Chops

4 pork chops, cut 3/4-inch thick
3 tablespoons butter or margarine
1 small onion
1 (8 ounce) package herb stuffing mix
1/2 cup water
1/4 teaspoon dried oregano
1 (8 ounce) can pizza sauce
1 (3 ounce) can sliced mushrooms
1 cup shredded mozzarella cheese

Preheat oven to 350 degrees F.

Chop onion and saut