Grease a 37 cm x 27 cm baking tray with oil or butter.
Gently pull the kadaifi pastry apart to separate the strands. Lay half of the pastry in the baking tray in an even layer and press it down firmly.
Scatter the ground walnuts over the pastry evenly, followed by the raisins. Lay the remaining kadaifi over the top evenly and press down firmly. Pour the melted butter over the top of the pastry and bake it for 1½-2 hours, or until the top is golden.
Note – I increased the heat to 220°C for the last 20 minutes as my oven can be a little temperamental.
While the kadaif is baking, make the syrup.
Allow the kadaif to cool completely before pouring over the syrup.
Put all the syrup ingredients into a saucepan over medium heat, bring to the boil, then reduce to a moderate simmer. Let it simmer for 30 minutes. Strain out the zest, then pour the hot syrup over the cooled kadaif.
Cut the kadaif into squares while it’s still warm, then let it cool completely before serving. Prior to serving, scatter small mounds of the coarsely chopped walnuts on top of each square of kadaif.
Store in a sealed container in the fridge. It’s best eaten at room temperature, but is still very nice eaten cold.