Add milk, vanilla, and chia seeds to a lidded container. Mix thoroughly and cover. Place in the fridge for at least 4 hours, overnight is even better.
For the blueberry sauce, add blueberries and water to a saucepan over medium heat. Simmer gently until berries begin to burst and a thicker sauce begins to form. Remove from heat and refrigerate.
Portion the chia pudding into serving bowls or cups, and top with blueberries. Serve!