In separate small bowls with mixer on high speed, beat egg white and heavy cream until stiff peaks form; fold egg white mixture into cream. Fold in Sweet'N Low® and vanilla. Refrigerate.
Warm 4 stemmed glasses. In coffee pot, dissolve instant coffee in boiling water. Fill each glass two-thirds full with coffee and discard remaining coffee. Add 1/2 ounce Irish whiskey to each glass. Spoon 2 tablespoons cream topping onto each glass. Serve immediately.