Preheat the oven to 180C/350F/Gas 4 and grease a non-stick baking tray.
For the pistachio baklava, brush three sheets of filo pastry with the melted butter and stack them on top of each other on the prepared baking tray.
Mix the pistachios, almonds, sugar, cinnamon and nutmeg together. Sprinkle half of the mixture over the filo pastry and then brush a further three sheets of pastry with butter and layer over the top.
Sprinkle over the remaining nut mixture and top with four sheets of buttered filo pastry. Brush the top liberally with the remaining melted butter.
Using the tip of a sharp knife, carefully score the top layer on the diagonal creating a lattice effect. Take care only to cut halfway through the top layers of pastry.
Bake in the oven for 20-25 minutes, or until golden-brown and crisp.
For the syrup, bring the caster sugar, 200ml/7fl oz water and orange zest to the boil in a medium saucepan. Simmer until the sugar has dissolved and the mixture is syrupy.
Remove from the heat, add the orange juice and leave to cool slightly.
Drizzle the syrup over the freshly baked baklava.
For the nectarines, preheat the oven to 200C/400F/Gas 6.
Using a small knife scrape the seeds out of the vanilla pod and toss with the sugar and orange zest.
Place the nectarines into a non-stick roasting tray and scatter over the sugar. Squeeze over the orange juice.
Bake the nectarines in the oven for about 15-20 minutes, or until they are softened but still holding their shape. Reserve any of the cooking syrup to pour over the nectarines.
For the custard, heat the milk and cream in a pan and gently bring to the boil.
Pound the sugar and whole cardamom pods in a pestle and mortar until the pods are broken and the seeds are lightly crushed.
In a bowl, beat the yolks and cardamom sugar together. Remove the milk and cream from the pan and gradually pour over the yolks and sugar stirring continuously.
Strain the mixture back into a clean pan.
Return the pan to a low heat and stir continuously until the mixture thickens enough to coat the back of the spoon, but do not allow to boil.
To serve, cut the baklava into squares and transfer to a serving plate. Spoon the roasted nectarines alongside and spoon any syrup over the top. Dust with icing sugar to finish. Serve the cardamom custard alongside.