Heat oven to 350 degrees. In a 13x9 inch-baking pan melt butter. Stir in garlic, basil, and green onions. Dip both sides of fillet halves into seasoned butter. Set half of fillets aside and the other half place in pan. Layer with 2 to 3 slices of cheese and about a tablespoon of chopped tomatoes. Cover with remaining fillet half and sprinkle with Parmesan cheese. Bake for 25 to 35 minutes, or until fish flakes.