Bring water to boil, add pearls, cook 15–20 minutes, rest 10 minutes, coat with sugar.
Whisk cocoa with hot water and brown sugar until smooth.
Mix milk, cream, vanilla, and salt, then add the chocolate mixture.
Add pearls, ice, and optional syrup to glass. Pour chocolate milk over bar spoon for layered effect.
Top with more ice, insert wide straw, stir gently, and enjoy immediately.