Step 1

Preheat oven to 200°C. Line the base of a roasting pan with a tea towel, folded to fit.

Step 2

Place water and 270g (11/4 cups) of sugar in a small saucepan. Cook over low heat, stirring, until sugar completely dissolves. Increase heat to high and bring to the boil. Boil, without stirring, occasionally brushing down the side of the pan with a wet pastry brush, for 8-10 minutes or until golden.

Step 3

Pour the toffee into a deep, 20cm (base measurement) round cake pan. Place in the roasting pan. Set aside to cool and harden.

Step 4

Heat the milk in a saucepan over medium heat for 5 minutes (don't let it boil). Set aside for 5 minutes to cool. Stir in vanilla.

Step 5

Whisk the eggs, egg yolks, Cointreau and remaining sugar in a large heatproof bowl until well combined. Gradually add the milk mixture, whisking constantly. Pour the mixture through a fine sieve over the toffee.

Step 6

Add enough hot water to the roasting pan to reach halfway up the side of the cake pan. Cover the cake pan with foil.

Step 7

Reduce oven temperature to 160°C. Bake for 1 hour or until a knife inserted into the centre comes out clean or with just a little custard clinging to it.

Step 8

Remove cake pan from roasting pan. Set aside for 2 hours to cool. Cover with plastic wrap. Place in fridge for 6 hours or overnight to chill. Run a sharp knife around inside edge of the pan and turn onto a serving plate.