Heat the grill to high. Clean and oil well.
In a mixing bowl, combine the butter, garlic and pepper flakes. Set aside.
Place the oysters in their shell over the hottest part of the grill. Spoon the butter mixture on top of each oyster.
Close the lid and let cook for about 3 minutes. Open the lid and baste once more with the butter mixture. Continue grilling until the oysters puff up and the sides begin to curl in slightly.
Remove from the grill and top with the Parmesan cheese. Serve warm with toasted garlic bread, if desired.
