Pre-heat your oven to 200 C/ 400 F/gas 6.

Add 100g of the sugar, seeds from the vanilla pod, cardamom, rhubarb and apple to a sauce pan and cook for 10 - 15 minutes until the fruit becomes tender.

Remove from the heat and leave to cool. If there is a lot of liquid, remove the fruit only using a slotted spoon.

Remove the cardamom pods.

Stir the walnuts through the fruit mix.

Line a baking tray with baking paper.

Place a sheet of filo pastry on to the tray then brush with melted butter.

Sprinkle over 1 tsp of caster sugar.

Repeat the process with 3 more layers of filo pastry.

Divide the fruit mix along the shorter edge of the pastry sheets and roll into a log, tucking in the ends as you roll.

Brush with more melted butter and sprinkle over the last of the sugar.

Bake for 25 mins, or until the pastry is golden brown and crisp.

Once cool, dust with the icing sugar and then serve.