Fill mug with hot water and let stand for 2 minutes.
Pour out the water, Add sugar and whisky to bottom of mug, stir in whisky.
Place heavy cream in a mixing bowl and whip until thick and frothy, but still pourable.
Hold a spoon upside down over the mug and pour cream slowly over the spoon to allow the cream to float on top of the coffee.
Garnish with cinnamon or cocoa.