Combine the sultanas and rum, set aside.
Whisk the butter, sugar and salt in a bowl. Add the eggs one at a time and continue to whisk until the mixture becomes lighter in colour. Stir in the honey and vanilla seeds. Combine the flour and baking powder, stir in the apples, add to the cake mixture along with the sultanas and rum. Transfer the cake mixture to the prepared tin.
Bake for approx. 55 mins. in the lower half of an oven preheated to 180°C. Remove the cake from the oven, allow to cool a little, remove from the tin and leave to cool on a rack, dust with icing sugar.