Bring the bourbon or whiskey to a boil and cook until reduced to about 1½ cups. While the bourbon is reducing, combine the milk, egg yolks and sugar in the top of a double boiler and whisk together. Continue whisking and stirring until slightly thickened, about 10-15 minutes. Pour the custard base into a covered container, add the heavy cream and the reduced bourbon, cover, and refrigerate until chilled.
Freeze ice cream in an ice cream maker according to manufacturer's directions, then freeze fully in a covered container in the freezer.
Recipe by Cooking With MicheleĀ® at https://cookingwithmichele.com/2018/04/bourbon-ice-cream/