Let the sugar caramelize in a dry (stainless steel *) saucepan about a cognac color.
Remove from the plate and deglaze with the fresh, still hot espresso. Caution, considerable steam generation! Let cool down.
Separate 4 eggs, whip the cream and egg yolks in a bowl in a water bath until the rose. Mix thoroughly with the cooled espresso caramel solution. First cool in ice water to room temperature, then in the freezer or refrigerator to around 8 ° C, then put the mixture in the ice machine.
When the ice cream has about the consistency of soft ice cream, add 4 cl mocha or coffee liqueur. If a darker color of the ice cream mass is desired, this can be achieved by adding a little sugar color.
* Stainless steel pot is my favorite when it comes to caramelizing because the sugar color is best seen in it.
Without an ice cream machine, I would break the egg whites of 2 eggs into egg whites (firm) and fold them into the cold coffee, cream, egg yolk and liqueur mixture.
Brush a loaf pan with neutral oil or line it with cling film, pour in the mixture and let it solidify in the freezer for at least 6 hours at -18 ° C.
To serve: dip the loaf pan briefly in water, turn it over and open it with the edge. The ice cream dissolves and can be served sliced.