Split the vanilla pod in half lengthways and using a sharp knife scrape out the seeds.
Place the milk, cream, vanilla extract, vanilla pod and seeds in a saucepan over a moderate heat, stirring occasionally, until hot but not boiling.
Place the egg yolks and WHITWORTHS CASTER SUGAR in a bowl and whisk with an electric hand whisk for 2-3 minutes until thick and pale. Remove the vanilla pod from the cream mixture and slowly pour over the egg mixture, whisking until combined.
Pour the mixture back into the pan and stir over a low heat for 4 minutes until the mixture thickens and coats the back of a spoon.
Pour the mixture into a metal bowl and allow to cool, then cover and freeze for 1 hour, or until beginning to set at the edge.
Beat with an electric hand whisk for 1 minute, then cover and return to the freezer. Repeat at hourly intervals, 2 more times until mixture is thickening and smooth.
Add the chunks of banana, stir through and return to the freezer for the last hour.
Remove the ice cream from the freezer 10 minutes before you wish to serve it. Serve in scoops.
Alternatively you can use an ice cream maker- following manufacturer’s instructions.