Marble sliced loaf cake with vanilla-flavored icing

sugar 52.1% , fortified wheat flour 16.0% , egg 8.0% , soya oil 4.9% , water 3.4% , chocolate chunk 2.5% , fortified wheat flour 1.9% , butter 1.5% , buttermilk 1.3% , Modified starch 1.0% , whole milk powder 0.9% , cocoa processed with alkali 0.8% , wheat starch 0.7% , Raising agent 0.6% , natural flavouring 0.5% , salt 0.5% , E415 0.4% , soya lecithin 0.4% , E330 0.4% , E466 0.3% , icing 0.3% , corn starch 0.3% , buttermilk 0.2% , butter 0.2% , palm oil shortening 0.2% , corn syrup 0.2% , E412 0.2% , natural flavouring 0.2% , E471 0.2%