Preheat the oven to 300°F (150°C). Place the sugar and water in a saucepan over a medium heat. Cook without stirring, swirling the pan occasionally, until the caramel turns a deep golden brown.

Lightly oil individual metal molds or one baking tin, then carefully pour in the caramel, allowing it to run right to the edges. Take care as the liquid will be extremely hot.

Make the custard by whisking the eggs and sugar together in a bowl until light and frothy. Meanwhile, heat the cream and milk together in a saucepan over a low heat until steaming hot, but not boiling. Drizzle a little into the custard, whisking continuously, then slowly add the rest of the milk, whisking all the time.

Place the metal molds or baking tin into a large roasting pan. Add vanilla, then strain the custard into a jug, and gently pour over the caramel. Place the roasting pan in the oven, then carefully add boiling water around the molds or tin until it reaches halfway up the sides. Bake for an hour or until just set.

Allow to rest until the dessert reaches room temperature, then carefully turn out onto a serving plate.