In a food processor or blender, pulse the durian flesh until creamy. Add in the sweetened condensed milk and pulse a few more times till smooth.
In a separate bowl, beat the heavy cream with a hand mixer until soft peaks form.
Whisk in a quarter of the durian mixture to the cream, before folding in the rest of the mixture with the vanilla extract and salt using a rubber spatula.
Pour into a freeze-proof container, cover and keep it airtight, then freeze for at least six hours, preferably overnight.