2 1/2 cups whole milk
3 ounces very strong espresso
6 egg yolks
1 cup sugar
1 tablespoon vanilla extract
2 cups heavy cream
8 cups strong decaffeinated coffee, cooled
1/4 cup unsweetened cocoa powder
1. In a 3-quart saucepan bring the milk to a boil over medium-high heat. Remove from heat and add the espresso.
2. In a mixing bowl, beat the yolks until pale yellow. Gradually add the sugar and beat until light yellow ribbons form when the beaters are lifted. Stir in half of the hot milk, then stir in the remaining milk. Cook over low heat without boiling until the mixture coats the back of a spoon thickly and sets slightly, about 4 to 5 minutes. Stir in the vanilla and chill for 1/2 hour.
3. Whip 1 1/2 cups of the cream to stiff peaks and fold into the custard mixture. Transfer to an ice cream machine and freeze according to manufacturer`s instructions. (The semifreddo can be made up to 2 weeks in advance).
4. Whip the remaining 1/2 cup cream to soft peaks. Place 1 scoop of semifreddo in each of eight tall glasses. Pour 1 cup of cooled coffee over each scoop, dollop with whipped cream, and dust with cocoa.