To Make Glaze: Bring the cream, butter, corn syrup, and instant coffee to a boil in a small saucepan. Put the chopped chocolate in a small bowl; pour boiling cream mixture over it, and let it sit for 5 minutes. Whisk gently until smooth, then pour carefully over the Hawaiian Vintage Mocha Cake. Chill until the glaze sets. Serve at room temperature with whipped cream or ice cream.