Add sugar to a mug then pour over the hot coffee, stir to dissolve the sugar.
Add the whiskey and stir,
Lightly whip the cream to thicken to soft peaks. You can add a dash of sugar to sweeten if you prefer.
Add a dollop of cream on top of the Irish coffee and serve.
Notes
Good quality coffee makes all the difference, it must be strong and rich to make an authentic Irish coffee. I recommend using a French press or Cafetiere to brew your coffee.
Make sure to use Irish whiskey, it doesn't need to be expensive.
Use fresh heavy cream and avoid anything in cans.
If you want to add a caramelized flavor to the coffee you can use brown sugar instead of granulated.
I recommend whipping the cream by hand to avoid over whipping, the cream should resemble soft peaks so it's still smooth and creamy (see photos).
If you want to impress, warm up your mugs before making your cocktail this will keep it warmer or longer and makes it extra cozy!
If caffeine is not your friend or you're avoiding it you can use decaf coffee instead.