Combine sugar and water in a small saucepan and stir over low heat until sugar dissolves. Bring to the boil, then boil without stirring for 2-3 minutes until syrup has reached 112°C on a sugar thermometer.

Whisk egg whites in the bowl of an electric mixer until foamy, then, with motor running, gradually pour in sugar syrup and beat until mixture becomes thick and glossy.

Using a hand whisk, whisk 1/4 of the egg whites into the mascarpone to loosen, then whisk in remaining egg whites until combined.

Combine the coffee, rum and marsala, then dip biscuits in mixture, turning to coat both sides.

Place a layer of biscuits over the base of a 24cm square tin, approximately 4cm deep. Spread with half the mascarpone mixture, sift half the Dutch cocoa over and scatter with half the grated chocolate. Top with another layer of dipped biscuits, then remaining mascarpone and scatter with remaining sifted cocoa and grated chocolate. Cover and refrigerate for at least 6 hours or until firm.

To serve, use a large spoon to scoop out portions, and place into a white bowl.

• Use a vegetable peeler to achieve long curls of chocolate for a garnish on top.

Photography by William Meppem. Styling by Hannah Meppem. Food preparation by Kirsten Jenkins