Scrape out seeds from both halves of the vanilla bean using the dull edge of a knife. In a saucepan, combine the seeds, bean, double cream and milk and heat gently over low heat until just bubbly. DO NOT BOIL.
Combine egg yolks and 5 tablespoons caster sugar in a mixing bowl, mix well. Add the egg yolk and sugar mixture to the saucepan with the cream mixture and heat gently for another 5 to 8 minutes. Again, DO NOT BOIL as it will cause lumps to form.
Pour the mixture evenly into 6 ramekins. Arrange the ramekins in a baking tin, and then fill the tin with cold water halfway up the sides of the ramekins. Bake in the preheated oven for 35 to 40 minutes.
Once finished baking, remove ramekins from baking tin and allow to cool to room temperature. Place cooled ramekins into the fridge and leave to chill for 3 hours or more.
When ready to serve, preheat grill. Top each ramekin with caster sugar, spreading evenly over the top of each. Place the ramekins under the grill for 2 to 3 minutes or until the sugar turns golden brown and is caramelised.
Leave the crème brûlée to cool at room temperature for 2 minutes before serving.