"Rich, decadent custard-based alcoholic ice cream that our house guests rave about. This recipe records the best of several variations that I have tried for our family and friends. Warning: watch yourself, this ice cream has a high alcohol content but you will barely taste the alcohol."
Heat milk, sugar, and salt in a saucepan over medium heat, stirring constantly, until mixture is steaming, about 5 minutes.
Beat egg yolks in a measuring cup. Continue beating while gradually adding hot milk mixture, 1 tablespoon at a time, until yolk mixture measures about 1 cup. Pour egg-milk mixture back into the saucepan and add chocolate; stir until chocolate has melted, about 5 minutes.
Stir heavy cream, vodka, coffee-flavored liqueur, and vanilla extract into chocolate mixture. Refrigerate until completely cooled.
Pour mixture into an ice cream maker and freeze according to the manufacturer's instructions. The alcohol substantially lowers the freezing point so the ice cream maker will only bring the mixture to a cold slush. Allow ice cream to ripen in the freezer for several hours until firm.