In a glass jar or other container, whisk together the milk, protein powder, chia seeds, maple syrup, espresso powder, and vanilla. Allow to sit for 15 minutes.
After 15 minutes, stir again, cover, and place in the fridge for 8 hours or overnight.
In a small bowl, whisk together the plain Greek yogurt and 1 tbsp maple syrup. Spread it evenly over the overnight oats, then dust with cocoa powder and serve!