In a saucepan over medium heat, combine the coconut milk, chopped dark chocolate, cocoa powder, and salt.
Warm the milk until until it just starts to simmer and add the chocolate. Keep stirring until the chocolate is completely melted. Turn off the heat and stir in the chia seeds and vanilla, stirring constantly. If you just dump the chia seeds in without stirring, they’ll glob up into a big gelatinous ball.
Pour the pudding into small serving cups and refrigerate for at least an hour, until the mixture is very thick.