Place the tin of condensed milk in a pot of water and simmer for three hours, making sure the tin is always covered by water. Let it cool in the water and chill in the fridge before using it. Never open while warm.

When you are ready to make the tart, preheat the oven to 180C.

Melt the butter, then place the biscuits in a food processor and process until fine crumbs. Add the butter and process until it is fully incorporated.

Place the bananas in the oven for 15 minutes in their skin, then remove and cool slightly.

Pour the biscuit crumbs into a 23-centimetre tart shell then smooth and press it down with the back of a dessert spoon. Place in the fridge for an hour to firm.

Scoop out ¾ of the condensed milk, which has turned into a rich dark caramel, into a medium-size bowl. Cut open the bananas and mash the flesh into the caramel - don't worry about trying to get it very smooth. When the tart base is firm, pour the banana caramel in and smooth the top.

Put the chocolate in a bowl and heat the cream. As soon as the cream comes to the boil, pour it over the chocolate and stir gently until the chocolate is melted and smooth and shiny. Pour the chocolate over the caramel and smooth with a spatula.

Chill for 30 minutes before serving.

Tip: Cook your condensed milk days before and keep it in the fridge. Once cooked, it lasts for months unopened.