Preheat your oven to 400 degrees. Sift the first 6 ingredients together. Stir in your egg, butter and milk just till blended. Fold in the fruits. Fill paper-lined (or spray muffin pan with pam) tins full, and bake approximately 20 minutes. Beat the powdered sugar, milk butter and vanilla till smooth. Chill. After the muffins are cooled, pipe a cross with your icing, over each muffin.