In a mixing bowl, sift the flour and the baking powder together. Add the sugar and the salt. Make a well in the center, then break the eggs into the well. Mix thoroughly. Slowly pour in the milk, the rum, then the oil, stirring constantly. Butter an 8 inch round casserole with a lid. Pour in the batter and close the lid. Bake for 45 minutes without lifting the lid, in a medium oven (410 F). It is ready when a knife comes out clean. Keep baking if necessary. Unmold on a rack. Serve cold.
