Preheat an Irish coffee glass with hot water, then discard it.
Add the dark rum and coffee liqueur.
Pour in the hot coffee and stir once to combine.
Hold a bar spoon just above the surface, curved side up, and pour the lightly whipped cream over the back of it so it floats in a clean layer.
Do not stir. Serve immediately.
Tia Maria is Jamaican, made with Blue Mountain coffee, which is why this build works better than a generic coffee liqueur. Whip the cream only to the point where it just holds a ribbon — beat it stiff and it sits on top like a lid instead of a layer.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Jamaican Coffee.