In a high-speed blender, combine the milk, espresso, rolled oats, flaxseeds, hemp seeds, vanilla extract, and pitted Medjool dates. Blend on high until the mixture is smooth.
If using a Vitamix, start on variable 1, gradually increase to the highest speed, and blend for about 45 seconds until fully smooth.
Scoop the blended mixture into 4 glasses or small containers, dividing it evenly.
Top each serving with Greek yoghurt and generously dust with cocoa powder.
Refrigerate the glasses or containers for a few hours to set, but for the best results, let them chill overnight. This allows the flavors to meld and the texture to thicken.
