Preheat oven to 190' C and line muffin tin with paper cases. Sift the flour and baking powder inot a mixing bowl. Stir in the sugar and cranberries. In another bowl beat together the yogurt,egg and veg oil with a fork until evenly combined. Tip the yogurt mixture into the flour using a dessert spoon gently fold the ingredients together until only just mixed. (Don't over blend the ingredients or the muffins won't be as light ). Spoon mixture into the cases it should be the level of the tin. Bake for 12 - 15 minutues until risen and firm to the touch. When cool sprinkle with icing sugar.