Triple Cheese Grilled Cheese Sandwiches

I usually don't post sandwich recipes, but this one is SO GOOD!!!

Triple Cheese Grilled Cheese Sandwiches

1/4 cup butter, softened
1 tablespoon grated Parmesan cheese
8 slices rustic sourdough or Italian bread
8 slices provolone cheese
8 slices mozzarella cheese

Mix together butter and Parmesan cheese in a small bowl. Spread 1 1/2 teaspoons butter mixture on 1 side of each bread slice. Place 4 bread slices, buttered sides down, on wax paper. Top with provolone and mozzarella cheeses; top with remaining bread slices, buttered sides up. Cook sandwiches, in batches, on a panini press or in a nonstick skillet over medium heat, gently pressing with a spatula, 4 minutes on each side or until golden brown and cheese is melted.