01 - Pour the coconut milk and granulated sugar into a medium saucepan. Add a pinch of salt and stir to combine.
02 - Set the saucepan over medium heat and bring to a gentle simmer, stirring frequently until the sugar has dissolved completely and the mixture is smooth.
03 - Lower the heat to maintain a gentle simmer—avoid a full boil. Continue cooking for 35 to 40 minutes, stirring occasionally, until the liquid has reduced by roughly half and coats the back of a spoon.
04 - Remove the saucepan from heat. Stir in the vanilla extract if using. Allow the condensed coconut milk to cool to room temperature; it will continue to thicken as it rests.
05 - Transfer to an airtight container and refrigerate. The condensed coconut milk will keep for up to 1 week.