You will need a mug, preferably a glass one. Fill the mug with very hot water and let stand for 2 minutes.
Empty the water from the mug. Add the brown sugar, then add brewed coffee and stir.
Stir in the Irish Whiskey.
Place heavy cream in a mixing bowl and whisk until frothy, but pourable. You can also use an electric mixer.
Hold a spoon upside down over the mug and carefully pour the cream over the spoon, allowing the cream to float on top of the coffee. Do not mix.