Mix the chia base: In a jar or bowl, whisk milk, cooled coffee, sweetener, vanilla, cocoa powder, and a pinch of salt until smooth. Sprinkle in chia seeds and whisk well to prevent clumps.
Let it thicken: Rest for 10 minutes, then whisk again.
Cover and refrigerate for at least 2 hours, preferably overnight, until pudding-like.
Make the protein cream: In a separate bowl, stir Greek yogurt with protein powder until silky. Add a splash of milk if it’s too thick. Sweeten lightly if needed.
Layer like tiramisu: Spoon half the chia pudding into a glass, add a layer of the protein cream, then repeat.
Dust the top with cocoa powder.
Chill and serve: Let it sit 10–15 minutes so flavors meld. Top with shaved dark chocolate or cacao nibs if you like.