1. Make the syrup by boiling the water and sugar together until the sugar is dissolved and the syrup is thick and viscous. Add the lemon juice and honey and remove from the heat to cool. When cool refrigerate until ready to use.
2. Brush a 9"x13" pan with butter and lay half the filo sheets on it, brushing each sheet individually with melted butter before adding the next sheet.
3. Spread a quarter of the nuts that have been mixed with the ground cinnamon over the sheets of filo and then layer half the remaining sheets on top, again brushing each sheet individually with melted butter.
4. Then sprinkle over the rest of the chopped nuts and repeat with the rest of the filo pastry.
5. Using a sharp knife, cut through the baklava diagonally into diamond shapes. It is important to ensure it is well cut or it will be difficult to serve and eat when cooked.
6. Place the baklava in a preheated oven 350F/180C and bake until golden brown - approximately half an hour.
7. Remove from the oven and pour the iced syrup over the baklava immediately, particularly on the slashes.
8. Allow to cool before serving.