For the pastry

1. Using an electric mixer, cream butter and sugar until pale and fluffy. Beat in egg, then fold in flour until just combined.
2. Wrap dough in plastic wrap and rest in the fridge for at least 20 minutes.
3. Heat oven to 150°C (300°F). Roll dough thinly, lightly grease 8 x 10cm (4 inch) loose-bottomed non-stick tart tins, and rest for a further 20 minutes.
4. Bake pastry cases blind (line with baking paper and fill with baking beans) for 10 minutes or until golden brown.
5. Take out the paper and beans and allow to cool; place the tarts on a baking tray.

For the caramel

1. Melt butter and brown sugar in a heavy-based saucepan over low heat, stirring until the sugar has dissolved.
2. Add condensed milk and bring to a rapid boil for about a minute, stirring constantly until a thick, golden caramel forms.
3. Add salt incrementally and check for taste.
4. Spread caramel in cooled pastry cases to about 1cm (1/3 inch) thickness. Allow to cool.

For the chocolate custard

1. Turn oven to 100°C (212°F). Heat cream in a pot until just about to simmer.
2. Take off heat and add chocolate; whisk until melted and combined.
3. Whisk in yolks one at a time, then mix in the salt.
4. Leave to rest for about 10 minutes to cool, then stir and pour over the caramel layer.
5. Cover the tarts with foil and bake for about an hour, or until the filling is just set with a slight wobble in the centre.
6. Take tarts from the oven and allow to cool to room temperature.

To serve

1. Slice bananas diagonally and layer gently over the cooked custard.
2. Garnish with shaved chocolate and serve with whipped cream.