Add 30 g muscavado sugar and coffee liqueur to 500 ml espresso to taste. Mix in the gellan gum and bring to a boil. Immediately pour onto a tray in a thin layer, then leave to cool. When cool, cut into thin strips.
Chocolate Sponge Cake
Melt the dark couverture chocolate over a water bath or in the microwave and allow to cool a little. Mix the eggs and egg yolks together with the confectioner's sugar and salt. Stir in the wheat flour and melted couverture chocolate. Stir to form a smooth mixture. Pass the mixture through the iSi funnel & sieve directly into a 0.5 L iSi Whipper. Screw on 1 iSi cream charger and shake vigorously. Grease several small molds with butter and fill one-third of each with the mixture. Bake each in turn in a microwave for 40 seconds.
Soak the gelatin in cold water. Heat 100 ml (3.4 fl.oz) of espresso (to 60 °C or 140 °F), add 75 g sugar and dissolve. Squeeze out the gelatin and dissolve in the warm espresso. Mix 225 ml of cold espresso together with the heavy cream, and add to the espresso-sugar-gelatin-mixture. Pass through the iSi funnel & sieve directly into a 0.5 L iSi Whipper. Screw on 1 iSi cream charger and shake vigorously. Refrigerate for 1-2 hours.