Preheat the oven to 160°C.
First, make the syrup by placing the sugar, water and orange flower water in a saucepan. Bring to the boil, stirring occasionally, then simmer for 15 min. cool to room temperature.
Spread the almonds, walnuts and pistachio nuts on to a baking sheet, transfer to the oven and cook for 6 minutes until golden brown.
Place the cooled nuts in a food processor and blend to a coarse texture. Stir the cinnamon through the nuts.
Cut the filo pastry sheets into equal sized pieces. Place one sheet of pastry on to a lined baking tray, brush with melted butter. Repeat 14 more times to give a layer of pastry 15 sheets thick. Next, spread the nut mixture over the pastry. Top with the remaining sheets of pastry, this time sprinkling a little butter between each sheet. Cut the baklava into rectangles or diamond shapes. Pour over the remaining butter and bake in the oven for 40 - 45min or until golden brown.
Remove from the oven and allow to cool a little, before pouring the syrup all over. Leave to stand at room temperature for 3 hours, so that the baklava can absorb the syrup.
Serve at room temperature, with a glass of water.
«Work quickly with the filo, as it dries out and becomes impossible to work with. You can cover the sheets of filo with a clean tea towel in order to keep them from drying too quickly.»