Mushroom Parmesan

INGREDIENTS

• 1/4 cup grated Parmesan
• 1/2 teaspoon salt
• 2 tablespoons butter, cut into small pieces
• 1/2 cup shredded mozzarella cheese
• 3 tablespoons extra-virgin olive oil, plus extra for greasing the grill pan
• 1/4 teaspoon freshly ground black pepper
• 1 cup marinara sauce (store bought or homemade)
• 4 to 6 portobello mushrooms