Cut the filo pastry sheets to the size of your baking tin; a good size is 25cm x 35cm.
Brush the baking tin liberally with melted butter. Layer half the filo pastry sheets in the tin, brushing every second sheet with butter.
Spread cashews and pistachios evenly over the pastry. Cover with the remaining filo, brushing every second sheet with butter. Do not butter the top.
With a sharp knife, make parallel cuts on the diagonal about 3.5cm apart through to the base of the tin and cut on the diagonal the opposite way to create diamond shapes. Brush the remaining butter on top.
Bake for 10 minutes, reduce the temperature to 180⁰C and bake for another 35 minutes or until golden. Remove from the oven.
For syrup, place water sugar and cloves in a saucepan and over a high heat bring to the boil, do not stir, gently agitate, swirling the liquid occasionally until sugar has dissolved and liquid is boiling. Reduce heat to low and simmer for 5 minutes or until thick and syrupy.
Pour hot syrup over the hot pastry, sprinkle with pistachio nuts and leave to cool.