Here's the best recipe I've found.
The Irish Coffee
Originally prepared by Joe Sheridan at Foynes “flying boat" terminal in Dublin , commonly known now as Shannon Airport . Joe and his Irish coffee later found a home at the end of the Hyde Street cable car line on San Francisco 's waterfront at the Buena Vista Cafe.
Never use canned cream in an Irish Coffee. Whip your own cream without sugar by placing a stainless steel bowl or pitcher in the fridge until it is very cold . Start with very cold heavy cream and whisk or whip to just under stiff so the cream has no bubbles and will still pour slowly. Always sweeten the coffee using brown sugar or brown sugar syrup. Finally don't drown the drink in coffee, about 4 ounces is all you need. Try to find the classic stemmed Irish Coffee glasses, because of their size they will force you to use the right amount of coffee. Those are the tricks we use in the business to make drinks bartender proof
1 1/2 oz. Jamesons Irish Whiskey
1 oz. Brown Sugar Syrup
Lightly Whipped Unsweetened Cream
Combine Whiskey, coffee and syrup in an Irish coffee glass. Ladle one inch of cream on top.