Rinse a large, heat-proof mug with boiling water, add sugar, cinnamon stick, and a lemon or orange peel studded with cloves. Pour in enough boiling water to dissolve sugar and stir in rum. Fill mug with boiling water and place pat of butter on top of drink. Warm Demerara rum in a ladle, into which you have put a pinch of sugar, by partially immersing the bowl in hot water. Ignite rum and pour blazing into mug. Add a little additional butter, if you with, and sprinkle with nutmeg.
Serve in a Irish Coffee Cup