Pre-heat the oven to 160 degrees. Blitz the pistachio nuts to a fine crumb. Keep back two tablespoons for the top. Cut the filo pastry sheets into quarters
In a lined 9x9 inch baking tin, place a layer of filo (two quarters, overlapping), a drizzle of fruit syrup, a sprinkle of pistachio nuts and spray with low calorie cooking spray. Repeat this process until you have used all of the filo (It will be around 15 layers). Top with more fruit syrup and the pistachios which were held back earlier.
Cook in the oven for 25 minutes, keeping a close watch on it in case it starts to burn. Leave to cool for 10 minutes in the tin.
Take out, cut into 16 rectangular pieces, and then cut each rectangle diagonally to make 32 triangles. Serve straight away!