Preheat oven to 425. Open oysters, keep in the the deep half of their shells. Set aside.
Heat butter in a skillet; add onion, garlic, salt and pepper, saute 2-3 minutes. Add bread crumbs to pan until crumbs are moistened.
Spoon mixture onto each of the oysters, top with the mixture and cover with grated cheese.
Bake until top is golden brown. Approximately 15-20 minutes.