Place 150 grams of dark chocolate in a food processor and blast until it looks like sugar. Heat up 150ml cream with the zest of 1/2 and orange, 1 table spoon of butter and 1 table spoon of fresh orange juice. When the cream is almost boiling take it off the heat and pour straight into the food processor and blast until the consitency is smooth and silky. Pour in a bowl and leave in the fridge.
Make the truffle mix in the evening and leave to set over night and roll the little chocolates the next day.