Heavily butter a 2-quart gratin or flat casserole ovenproof dish. Scatter very very coarsely broken (with your hands) crackers in the bottom of the dish. Top with a few oysters. Add more broken crackers and a few pieces of butter. Season with freshly ground black pepper.
Repeat layering of oysters and crackers two more times, ending with broken crackers.
Pour around remaining oyster liquor. Dot with butter. Add half and half just to top of crackers. Season again with a few grinds of pepper. Bake in preheated 400-degree oven for 35-40 minutes or until puffed and golden. Serve IMMEDIATELY.