Husk the corn. Coat each piece all over with olive oil spray.
To Grill: Preheat grill to medium-high. Add corn to grill. Grill corn, turning occasionally, until charred and tender, 8 to 12 minutes total. If it starts to stick, coat with more olive oil spray.
To Broil: Preheat broiler. Line a baking pan with foil. Place corn on the pan. Broil for about 6-7 minutes until charred (browned). Turn over and broil about 6 minutes more.
Remove corn from heat and sprinkle with a little salt and garlic powder all over each piece. Sprinkle the top of each ear of corn with ¾ tablespoon of Parmesan cheese.