Combine the coconut milk and dates in a small saucepan. Heat over medium heat until milk is warm (but not boiling), and dates are softened, about 5 minutes.
Whisk in the cacao powder, vanilla, and salt.
Transfer mixture to a blender and blend until smooth.
Place the liquid in a bowl with an airtight lid and add the chia seeds. Shake thoroughly to combine.
Refrigerate for at least 2 hours, stirring every half hour or so until thickened.