Heat oven to 190°C/Fan 170°C/Gas 5.
Put 100ml water in a saucepan with the syrup ingredients, and bring to a boil. Simmer for 2-3 mins, then set aside.
Put the nectarines in a baking dish, cut side up. Strain the syrup, pour it over the nectarines and bake for 15 mins, or until the fruit is soft.
Meanwhile, mix the Mascarpone, orange zest and honey in a bowl until smooth.
Serve the nectarines drizzled with syrup from the baking dish, and topped with a dollop of mascarpone, with the cantuccini biscuits and pistachios scattered over