Mix your espresso or coffee granules with the boiling water and pour into a shallow dish or takeaway container.
Take your mascarpone, double cream and sugar and whisk together in a mixing bowl until smooth and the consistency of thickly whipped cream. If using, whisk in your alcohol, 1 tablespoon at a time, until fully combined.
Take your ladyfingers or sponge/Madeira cake strips and very quickly roll each one in the coffee/liqueur mix for about 2-3 seconds. The key is to avoid sogginess by over-soaking them. If there is any leftover coffee/liqueur mix, either drizzle it over the top layer of soaked ladyfingers/sponge cake in the container, or drink it.
Assemble and layer the dessert in the container of your choice. You can also make individual portions in 6 wide-bottomed glasses or teacups, if you prefer.
Start with a layer of the soaked ladyfingers/sponge cake and then slather on half of your cream mix. Do one more layer of the soaked ladyfingers/sponge and finish with the remaining cream mix.
Decorate with the cacao nibs and sifted cocoa powder, then cover (if there’s enough spare space at the top of the dessert to do so) and leave to set in the refrigerator for at least 2 hours or ideally overnight.