Bring the sugar and water to boil in a large heavy based pan until the sugar syrup thermometer reaches 115°C/soft ball stage.
Quickly and carefully add the ground cashew nuts, vanilla extract and cardamom seeds. Mix together until the mixture resembles a non-sticky dough.
Place this mixture in the greased pan and smooth the surface as much as you possibly can because you are going to cover with chocolate. I use a hot metal spoon to get a completely flat surface. Cool over night, but not in the fridge.
Melt the chocolate over a bain-marie and cover the set fudge with the melted chocolate. Smooth over and allow to cool at room temperature until the chocolate sets.
Cut the chocolate fudge into diamond shapes or any other shape you may wish to. Decorate as you wish. I used sugar flowers and lots of glitter.