Add the coconut milk and sugar to a sauce pan and bring them to a boil over medium heat. If adding the sea salt or vanilla add them here.
Once boiling, turn down the heat and let it simmer for approximately 55-60 minutes, stirring frequently to prevent the sugar from sticking to the pot and the milk from clumping.
You will know it's done when it has reduced in volume by about half and has slightly darkened in colour.
Let the condensed milk cool completely and then use as you wish.
Notes
This recipe yields ~2 cups of condensed milk.
Nutritional values are an estimate and will vary depending on the exact ingredients used.
The colour of the condensed milk will vary depending on the type of sugar you use - it can be slightly darker or lighter.
Store this condensed milk in an airtight container or jar in the fridge for up to 7 days.