Add banana, brown sugar and butter to a skillet and fry on a low-medium heat until cooked through. Remove from the stove top.
Add milk, cream, and sugar to a saucepan and cook on medium-high heat until simmering. Take off heat.
Whisk yolks until pale then slowly pour a cup of the hot milk into the yolks. Once combined, whisk back into the saucepan of milk. You now have the makings of a delicious custard base.
Heat custard base for about 5 minutes on a medium heat until it thickens and coats the back of a spoon. (Don't allow to boil).
Blitz the custard base with the bananas until well combined.
Pour into an airtight container and allow to cool in the fridge for at least 3 hours (preferably overnight).
Churn in an ice cream machine as per manufacturer's instructions.
Add to an airtight container and freeze for 2 hours or until hardened.