Melt the chocolate chips carefully (not too hot!) In a water bath. If you don`t use chips, you have to chop the couverture beforehand.
Heat the cream and dissolve the espresso powder in it. Stir the hot cream into the melted chocolate. This is best done with a whisk until the two have combined.
Fill into portion glasses and refrigerate overnight.
Depending on your taste, you can garnish with whipped cream and / or cocoa powder shortly before serving.