Preheat oven to 400 degrees. Line a baking sheet with foil. Brush half the butter on foil. Lay 6 slices of bread down on the butter. Top with mozzarella cheese, ham, spinach, salami, pepperoni, pepperoncini, and provolone cheese.
Top with remaining bread, and brush with butter.
Take another sheet pan, and place on top to keep the sandwiches weighed down.
Bake for 10 minutes. Remove the pan, and bake an additional 20 minutes.
Garnish the tops with parmesan and fresh parsley.
Keyword italian subs, sheet pan, summer dinner, summer recipe, summer sheet pan