In a small bowl, mix together the butter, Parmesan, Italian seasoning and crushed red pepper. Brush one side of each slice of bread with this mixture.
Heat a nonstick skillet over medium heat. Lay one piece of the bread, butter-side down, in the skillet. Spread 1 tablespoon marinara sauce on the bread and layer on the mozzarella, provolone, pepperoni, pepper slices, olives and basil leaves. Top with the second slice of bread, butter-side up. Toast in the skillet, flipping as needed, until the bread is golden and the cheese has melted, 4 to 5 minutes.
Remove from the skillet and slice in half. Serve with the remaining 1/4 cup marinara on the side.