Soft bun with sultanas and lemon custard

wheat flour 41.1% , sugar 16.2% , water 9.5% , sultana 10.0% , palm oil 3.7% , whole milk 2.8% , free range egg white 2.2% , free range eggs 2.0% , glacé cherry 2.0% , invert sugar syrup 1.3% , rapeseed oil 1.2% , lactose 1.1% , milk powder 1.0% , E450 0.9% , E500ii 0.8% , E450iii 0.8% , E472c 0.7% , E472e 0.7% , E435 0.6% , yeast 0.6% , flavouring 0.6% , glucose syrup 0.6% , E160a 0.5% , salt 0.0% , lemon comminute 0.0% , modified corn starch 0.0% , modified tapioca starch 0.0% , E401 0.0% , E406 0.0% , E202 0.0% , E300 0.0% , lemon oil 0.0% , E330 0.0%