In a large saucepan or Dutch oven, combine the beans with the garlic and 6 cups cold water. Bring to a boil, reduce heat to a simmer, cover the pot and continue to cook the beans until just beginning to soften, about 30 minutes. Add the coconut milk and thyme sprigs and continue cooking until the beans are soft, 45 minutes to 1 hour longer.

Add the scallions, butter, salt, Scotch bonnet chile, and allspice and stir to combine. Cover and let sit until scallion has softened, 2 to 3 minutes. Return liquid to a boil and add the rice to the pot. Stir to combine well and return to a boil. Stir once again, cover the pot, reduce heat to low and cook, stirring once after about 5 minutes, until rice has absorbed the liquid and is tender, 25 to 30 minutes. Remove from the heat and set aside to sit, undisturbed, for 10 minutes. Remove the chile, scallions, and thyme sprigs, fluff with a fork, and serve.