Coarsely chop the chocolate coating and melt in a hot water bath. Dip 4 teaspoons into the couverture. Place on a piece of baking paper and chill for about 30 minutes
Put the rest of the couverture in the disposable piping bag and cut off a small tip. Decorate 4 glasses (each containing approx. 1/4 l) with it from the inside. Put the glasses also cold
Whisk the egg yolks and sugar with the whisk of the hand mixer until thick and creamy. Stir in rum
Stir about 400 ml of boiling water into the egg foam. Pour the eggnog into the glasses. Put one scoop of ice cream into each glass and serve immediately with the chocolate spoons