Preheat a charcoal grill.
Put the butter in a pot on high heat and bring to a boil. Make clarified butter by scooping all of the foam that rises to the top and discarding it. Add garlic powder or fresh garlic to the butter.
Put oysters on an open flame grill and sprinkle Parmesan over top, making sure not to completely cover the oysters. Let them cook until the cheese starts to brown, about 2 to 3 minutes. Then drizzle the garlic butter generously over the oyster, cook another 1 to 2 minutes and remove from heat. Serve immediately with extra butter, if desired, and with bread or breadsticks.