1.Make poached peaches and nectarines. Make small cuts into the base of each fruit. Combine sugar, the water, vanilla seeds and bean, and rind in a large saucepan.
2.Cook over medium heat, stirring, until sugar has dissolved. Bring to the boil, add fruit; return to the boil. Immediately reduce heat to a very gentle simmer; place a small plate over fruit to weigh them down in the liquid.
3.Poach fruit for 5 minutes or until just tender. Remove plate; remove fruit with a slotted spoon. Discard rind. Reserve 2 cups of poaching liquid (keep the remaining liquid for another use); cool reserved liquid and fruit separately.
4.Beat sugar and egg yolks in a small bowl with an electric mixer for 5 minutes or until pale and tripled in volume. Fold through mascarpone.
5.Beat egg whites in another small bowl until soft peaks form. Fold gently through yolk mixture until smooth.
6.Slip skins off fruit. Halve fruit; discard stones. Cut fruit into thin wedges. Stir liqueur through reserved poaching liquid.
7.Cover bases of eight 1-cup (250ml) serving glasses with a layer of mascarpone mixture.
8.Working in batches, dip enough biscuits into poaching liquid to cover top of mascarpone mixture (break biscuits to fit, if necessary); top with another layer of mascarpone mixture, then top with fruit.
9.Cover with plastic wrap; refrigerate until ready to serve.
This recipe must be eaten on the day it is made. The poached fruit will keep for 2-3 days, covered, in the fridge, but the fruit will generate a lot of liquid. Reduce leftover liquid to a syrup by simmering gently, and pour over ice-cream.Note