Add some coffee powder in boiling water and prepare a coffee decoction. Pour in a tray to cool slightly. In a bowl, whisk the mascarpone cheese, fresh cream, condensed milk, lemon zest, and lemon juice. Dip the Italian lady's fingers in the coffee tray and arrange in a deep square bowl to make a layer. Add a layer of the prepared cheese mixture on them and dust cocoa powder. Similarly, make another layer of lady's fingers and pour the prepared mixture over it. Drizzle with the remaining coffee mixture and dust with cocoa powder. Garnish with grated dark chocolate and serve.