For the raisin biscuits, cream the butter, sugar, orange zest and egg whites in a food processor. Add the flour and stir for a few minutes.
Line a baking tray with baking paper. Preheat the oven to 200°C. Using a teaspoon, place the mixture in heaps on the baking paper. Place a raisin on each heap.
Bake for 5-10 minutes until the raisins have taken on some color.