Add the sugar and, milk into a pot and place onto a low heat. Simmer away until it's smooth. Add the butter and salt and stir through. I like to add a sugar thermometer to regulate the temperature. You're aiming for 130°C.
Add the condensed milk and bring it up to a boil (stir continuously to stop it catching on the bottom of the pan). Simmer for about 20 minutes until the mixture darkens to a caramel colour, stirring continuously. Then add the vanilla.
Take off the heat, quickly beat the mixture with a whisk and pour it into a 30cm by 40cm deep dish lined with parchment paper. Leave to cool for 30 minutes before scoring into cubes. Leave to harden for a further hour then you're ready to get hyper on your delicious sugar fix!
