Put the cashew nuts in spice grinder or blender and grind to a powder.
Remove the seeds from inside the cardamom pod and crush to a powder using a pestle and mortar.
Put the water and sugar in a small saucepan and leave to boil. Don't stir or it will crystallise.
Stop boiling the sugar when it begins to form threads when you dip a spoon in. This should be about 3 minutes after it has started boiling. Take off the heat. Add a pinch of the ground cardamom. Then the ground cashew and stir in quickly. It should be the consistency of a thick dough. Add a splash of water if it won't all combine.
Put the dough onto grease proof paper and flatten until it is about ½ to 1 cm thick. Leave to cool for half an hour in the fridge.
Cut into diamond shapes and top each one with a pistachio. Store in a cool place.
Nutritional information is approximate and a guideline only.