Step 1

Add all ingredients except for the whiskey to a pot over medium-low heat.

Step 2

Heat the mixture, whisking until the sugar is dissolved and the cocoa powder is well incorporated. The mixture should be steaming hot, but it should not simmer or boil. Keep over medium-low heat for a few minutes, then remove from heat.

Step 3

Let it cool to room temperature, then whisk in the Irish whiskey.

Step 4

Transfer to a jar or glass bottles with a lid, then store in the refrigerator for 1-2 months. Shake well before each use.