Pre-heat oven 170°C.
To make the caramel, pour the sugar and 6 tbsp of water into a clean stainless-steel pan
Dissolve the sugar slowly, stirring with a wooden spoon over a low heat
When there are no sugar granules left, stop stirring and boil until the sugar turns a dark golden colour
Remove immediately from the heat to ensure the caramel does not burn
Quickly pour the caramel into a 1l capacity cake tin or a (16cm diameter) crème caramel stainless-steel pan
Set aside to cool and become hard (do not put in the fridge because the sugar will absorb moisture and go soft and tacky)
Once hard, butter the sides of the tin above the level of the caramel
To make the Navel orange custard mixture, whisk all the ingredients together in a bowl until well mixed. Pour the mixture into the prepared tin
Stand the tin in a roasting tin and fill the tin half-way with boiling water from a kettle
Cook in the oven for about 1 hour or until the custard has set. Do not overcook the custard
Take the tin out of the oven, remove from the tray and set on a cooling rack. When cool, transfer to the fridge overnight so that the caramel is absorbed into the custard.
To serve, loosen the sides of the custard by tipping the tin and loosen with a small palette knife round the edges.