Melt the sugar and water over a low heat until melted
Once melted, turn up the heat and allow it to bubble away until it has turned golden brown
Remove from the heat, place in the sink, and immediately pour 100ml of cold water into the pan, standing back so it doesn’t spit at you.
Once it stops bubbling, stir it until you have a thin syrup.
Leave this to cool and then mix it together with the custard, cream and bananas.
Churn in an ice cream maker (according to the manufacturer’s instructions), and then finish to set in the freezer.
If you don’t have an ice cream machine you can freeze it, but make sure you are available to whisk it every 20 minutes until it has set – this could take most of the day.