- Preheat oven to 350°F/180°C/Gas 4. Grease and line a loose bottomed 23cm / 9″ cake tin.
- Sieve the flour, icing sugar and cornflour into a bowl. Rub in the butter/margarine until mixture resembles fine breadcrumbs.
- Press into the prepared tin and bake in preheated oven for approx 20 minutes until golden in colour. Leave to cool in the tin.
- Place the unopened tin of condensed milk in a saucepan covered with sufficient water to cover top of tin.
- Bring to the boil and then reduce to a low simmer for 3 hours. Make sure the level of the water does not fall below the tin of condensed milk during simmering.
- Remove tin from saucepan and allow to cool. This can be done a few days in advance.
- Spread toffee over the cold shortbread. Gently remove from the cake tin and place on a serving plate. Arrange the sliced bananas on top of the toffee, cover with the whipped cream and decorate with grated or flaked chocolate.