For the rest of the recipe:
2 cups whole milk
1/4 cup regular sugar
1 tsp. vanilla extract
¼ tsp. salt
Pre-heat oven to 300F/150° celsius.
To make the caramel: On low heat, melt the caster sugar and water in a saucepan. Let the mixture melt. It’s very important not to stir until the color starts to turn golden. At this point, shake the pan, until the color slowly turns to caramel golden brown. Take away from heat, and pour immediately into the mold. Swirl your mold in a circular motion so the edges get covered in the caramel.
Heat milk in a saucepan. When it starts to boil, lower the heat, and add sugar, vanilla and salt. Stir, leave for one minute and set aside.
Whisk four eggs in a large bowl, and pour in the warm vanilla milk. Make sure to whisk continuously while you are doing this so the eggs don’t coagulate. Pour the egg mixture into the caramel-lined mold.
Place your mold in a large roasting tin, pour hot water so it comes up to nearly two-thirds of the mold. This process is called ‘bain-marie.’ Bake for 55 minutes—if your knife comes out clean then it’s ready. It should feel springy and firm to the touch. Remove from the oven and leave to cool completely. Once cool, leave in the fridge for a least an hour so it chills.