Prepare macaroni and cheese dinner according to package directions. Then add tuna, peas, cheddar cheese, milk, Italian seasoning, salt, and garlic powder. Mix well. Pour into a microwave safe dish. Cover with vented plastic wrap and microwave on high for two minutes. Stir and continue heating on high for three minutes more, or until cheese has melted and mixture is heated through. Sprinkle with parmesan cheese.