Heat the water, cinnamon sticks, allspice berries and sugar in a small saucepan.
As soon as the liquid begins to boil, lower heat to low and allow ingredients to infuse for approx. 15 mins.
Add coffee to liquid and stir until the coffee has combined with the liquid, then remove the pan from the heat and allow to steep for 5 mins.
Strain coffee mixture into a jug, then add rum and stir.
Place two scoops of ice cream into each sundae glass.
Then pour equal amounts of coffee over each mound of ice cream.
Serve immediately