Preheat the oven to 180 °C (355 °F), rack in the middle.
Using a pastry brush coat the bottom of 400 mm x 230 mm x 50 mm (15 3/4″ x 9″ x 2″) baking pan.
In a medium size mixing bowl mix together ground walnuts, lemon zest, vanilla sugar and raisins. Divide the mixture into 5 equal parts, set aside.
A filo pastry package contains 18 sheets. We will use 6 groups of 3 sheets. Line the bottom of the baking pan with the first group of 3 filo pastry sheets. Fold in excess sheet area to match the size of the baking pan.
Brush the filo sheet with vegetable oil.
Evenly spread the first part of the walnut mixture.
Lay over the second group of 3 filo pastry sheets, fold in the ends to match baking pan size. Repeat the same process of oil brushing and walnut mixture spreading until 5 layers are created. The last and the top will be filo sheet group layer with the edges folded under to create a smooth top surface.
With a sharp knife carefully cut the stacked pastry into 38 mm (1.5″) squares. To prevent the pastry sheet from slipping away use a plastic ruler to press down while at the same time using the ruler edge as a knife guide.
Bake for about 30-40 minutes or until golden brown. In the last 5-10 minutes prepare the sugar syrup, it is important that the syrup is hot at the same time when pastry is baked.
Syrup
Add sugar and water to a medium size sauce pan. Stir until sugar is completely dissolved. Over medium high heat bring it to a full boil and then add sliced lemon and cinnamon stick to it. Reduce temperature to low heat (3 out of 10) and cook for 5 minutes.
Assembly
After removing cinnamon stick and lemon slices ladle the syrup along the pastry cut edges. Spread lemon slices on top of it. Return the baking pan back to the oven, open the oven door and let it cook for 15-20 minutes.
Remove the baking pan from the oven and let it cool on a cooling rack completely.