Melt the chocolate with the rum in a
heatproof bowl set over a pan of gently simmering water. Whisk
together the eggs and sugar until light and fluffy, then fold in the
cornflour and flour. Stir in the chocolate mixture. Spoon into a
greased and lined 20 cm/8 in cake tin (pan) and bake in a preheated
oven at 190ºC/375ºF/gas mark 5 for 10-15 minutes until springy to the
touch.