To assemble: Pour the liqueur in a tall coffee cup, preferably crystal - as to see inside the dessert. Scoop one large scoop of vanilla gelato (or ice cream) in the bottom of the glass. Finish with a shot of freshly brewed espresso.

Combine the milk, cream and sugar in a medium-sized nonreactive saucepan. Add the vanilla beans and seeds to mixture, or add the vanilla bean extract. Bring the mixture to a boil over medium heat, stirring from time to time, until the sugar is dissolved, about 10 minutes.

Meanwhile, beat the egg yolks in a small bowl. Slowly whisk 1/2 cup of the hot milk-cream mixture into the yolks, then return the warmed yolks to the milk-cream mixture, stirring continuously. Reduce the heat to medium-low and cook, stirring constantly for about 20 minutes until the mixture is thick enough to coat the back of a wooden spoon or measures 190 degrees F on an instant-read thermometer. Remove the pan from the heat and pour the mixture through a fine strainer into a metal bowl. Put the bowl on another bowl partially filled with ice and stir to chill completely. Transfer the liquid to the canister of an ice cream maker and freeze according to the manufacturer's instructions for gelato. When frozen, transfer the gelato to an airtight container and store in the freeze. Makes 1 quart.