Frangelico Ice Cream

1 1/2 cups heavy cream
1 1/2 cups milk
3/4 cup sugar
1 vanilla bean, split lengthwise
8 egg yolks
1/3 cup Frangelico

In a saucepan, bring to a boil the cream, milk, sugar and vanilla. Remove from heat. Whisk yolks in large bowl to blend. Gradually whisk hot cream mixture into yolks. Return to pan. Stir over medium heat until custard thickens and leaves path on back of spoon when finger is drawn across, about 7 minutes. Whisk in Frangelico. Refrigerate uncovered until cold. Process custard in ice cream maker according to manufacturer's instructions.