Slice: Preheat oven to 180 degrees C. Grease a 23x33cm baking tin.
Beat butter until creamy. Add half of the flour, the brown sugar, white sugar, egg, stewed apple, bicarbonate of soda and the mixed spice. Beat together until well blended. Beat in remaining flour and stir in sultanas. Spread in prepared baking tin.
Bake for 20-25 minutes or until toothpick in centre comes out clean. Cool in tin on wire rack. Drizzle with icing. Cut into bars.
Icing: Mix icing sugar, vanilla and milk. Mix to drizzling consistency.