2 oz. strong cold-brew coffee
2 oz. stout (such as AleSmith Speedway or Guinness)
1½ oz. Irish whiskey
¾ oz. simple syrup
1/2 ounce heavy cream
Freshly grated cinnamon stick (for serving)
Mix coffee, stout, whiskey, and simple syrup in a highball glass. Add ice to fill. Gently pour in cream so it gradually sinks into coffee; sprinkle with cinnamon.