In a bowl or jar, mix together milk, cacao powder, maple syrup and vanilla extract if using. Make sure cacao powder is evenly dissolved.
Add chia seeds and stir well. Allow to sit for about 2 minutes, then stir again. Allow mixture to thicken for about 1-2 hours until chia seeds have absorbed all liquid. You can store in the fridge or on the countertop.
Finally, add toppings of choice and enjoy!