Heat oven to 450 degrees with rack in center. Butter a shallow 9- to 10-inch baking or pie dish. Drain oysters, reserving the liquid. Check oysters for shells, and discard shells. Melt 3 tablespoons butter over medium heat in a medium skillet, and cook scallions until soft, 3 minutes. Stir in Worcestershire sauce and Tabasco Sauce. Transfer mixture to a medium bowl, and let cool.
Stir in oysters, 1/4 cup parsley, salt, and pepper. In a medium bowl, combine cracker crumbs and remaining 3/4 cup parsley. Melt remaining 11 tablespoons butter, and stir into crumb mixture. In a small bowl, combine 1/4 cup of the reserved oyster liquid with half-and-half. Spread an even, thin layer of the crumb mixture in the bottom of the baking dish. Cover with one-third of the oyster mixture. Cover with 1/2 cup crumb mixture, followed by one-third of the oyster liquid. Continue until all ingredients are used, two more times, ending with crumb mixture. Bake until golden brown on top, 25 to 35 minutes. Serve hot.