Fill a glass goblet with hot water to heat it up, then dump out the water.
Drop in the two sugar cubes or granulated sugar.
Pour the strong, hot coffee over the sugar cubes, to fill about 3/4 of the glass. Stir until the sugar is dissolved and mixed.
Add 1 ½ oz Irish whiskey (Old Bushmill’s, Jamesons) with a bit of room left in the glass for the cream.
Using a whisk, lightly whip heavy whipping cream in a small bowl until the cream is slightly thickened. Take care not to over whip (we’re not going for whipped cream). Turn a spoon upside down (bowl of the spoon facing down), and pour the thickened cream down the back of the spoon, layering onto the top of the coffee. Don't stir the cream into the coffee, to keep the layers visible. Serve immediately.