For making the tres leches cake:
1. Preheat the oven to 180°C (160° fan) | gas 4.
2. Grease four large individual pudding moulds with some of the softened butter.
3. Beat the remaining butter with the sugar, vanilla extract, and a pinch of salt until pale and creamy, 2-3 minutes.
4. Gradually stir in the eggs and beat the mixture until very fluffy.
5. Mix the flour, cornflour, and baking powder in a bowl and sieve onto the egg mixture, folding through.
6. Divide the batter between the pudding moulds and bake for about 20-30 minutes; a toothpick should come out clean from their centres.
7. Remove from the oven and leave to cool.
8. Briefly whisk together the evaporated milk with the single cream and milk in a bowl.
9. Prick holes in the cakes with a toothpick before soaking each cake with the milk mixture.
10. Cover and chill for at least 3 hours.
To serve the cake:
1. Cut the banana into 12 slices, on the bias.
2. Arrange on a lined tray and dust with icing sugar before caramelising with a chef's blowtorch or under a very hot grill.
3. Turn out the chilled cakes onto plates flooded with some milk, arranging the caramelised banana underneath the cakes.
4. Top with a squirt of whipped cream, a raspberry, and some mint before serving.