In a medium bowl, whisk together cocoa powder and about ¼ cup of the milk until smooth
Add remaining milk and maple syrup, whisking to combine
Add chia seeds and stir well
Let sit for 15-20 minutes, then stir again to break up any clumps
Cover and refrigerate overnight (or at least 4 hours)
In the morning, give it a quick stir and top with your favorite toppings