In a medium bowl, whisk together 1.5 cups milk, 3 tablespoons unsweetened cocoa powder, 2 to 3 tablespoons maple syrup (to taste), 1 teaspoon vanilla extract, and a pinch of salt. Whisk until the cocoa is fully dissolved and the mixture looks smooth.
Stir in 6 tablespoons chia seeds. Whisk for 30 to 60 seconds to distribute the seeds evenly. Let it sit for 5 minutes, then whisk again to break up any clumps.
For extra creaminess and protein, whisk in 1/4 cup plain Greek yogurt. For mocha flavor, add 1/2 teaspoon espresso powder. For warmth, add 1/4 teaspoon cinnamon.
Divide the mixture into 3 to 4 jars, filling them about three-quarters full to leave room for toppings.
Cover and refrigerate at least 2 hours, preferably overnight. The chia seeds will swell and set the pudding to a silky, scoopable consistency.
Stir each jar before eating. Top with sliced banana, berries, a sprinkle of cacao nibs, or a spoon of nut butter. Add a handful of granola if you want crunch.