Preheat the oven to 325ºF. Mix all with an electric mixer for five minutes. Grease bundt pan and lightly flour. Bake for one hour.
Meanwhile, combine rum, butter and sugar together in a saucepan. Bring to a boil. When cake comes out of the oven, pour one-third of this mixture into the bottom of the cake. Let sit for 30 minutes. Turn cake out onto a cooling rack. Paint a layer of the glaze all over the cake. Let harden. Paint another layer. Repeat until all the glaze is gone.