Preheat the oven to 350°.
In a saucepan, bring the beef broth and water to a boil. Add the rice, bring to a boil again, reduce heat, and simmer covered for 25 minutes. Drain any liquid remaining. Add 1/2 cup of the butter and hot sauce and stir; fluff with a fork.
Sauté the drained oysters in 1/4 cup of the butter over medium-high heat until the edges curl, approximately 3 to 5 minutes. Remove the oysters with a slotted spoon; set aside. Place half of the rice in a greased 13 by 9 by 2-inch baking dish. Cover it with oysters and sprinkle with hot sauce and salt and pepper, to taste. Top with the remaining rice.
In a saucepan, heat the mushroom soup over medium heat. Add the half-and-half, onion powder, and garlic salt. Pour over the oyster mixture. Bake for 35 to 40 minutes, until golden brown and bubbling. Garnish with parsley and red pepper flakes.