Cake: Sprinkle nuts in bottom of bundt pan. Mix all cake ingredients together. Pour over nuts. Bake 1 hour at 160ºC . Cool. Invert on serving plate. Prick top and drizzle and smooth glaze evely over top and sides. Allow cake to absorb glaze. Repeat until glaze is used up. Glaze: Melt butter in sauce pan. Stir in water and sugar. Boil 5 minutes, stirring constantly. Remove from heat and stir in rum.