Add Irish whiskey, coffee concentrate, simple syrup, and chocolate bitters to a mixing glass filled with ice.
Stir until chilled, and strain into a tall glass filled with ice cubes.
Float heavy cream on top and garnish with ground nutmeg.
Notes
*Doubleshot Coffee Company's Coffee Concentrate can be purchased online here. However, you can use any local coffee shop's concentrate or even make your own. I personally love the OXO cold brew makers. I own the 32 ounce model, but the new mini is really appealing too!