In a heavy medium saucepan, whisk egg yolks and sugar together until well combined. Slowly whisk in cream, then milk. Cook, whisking frequently, over medium heat, until a custard forms on the back of a spoon and a finger swiped across the back leaves a clean line. Remove from heat and stir in nutmeg, salt, and bourbon. Pour through a strainer into an airtight container and chill overnight. The next day, churn according to manufacturer's instructions. Return to airtight container and chill in freezer for at least three hours before serving.
