Whisk the cocoa powder into the almond milk first, until there are no dry lumps at all. Cocoa added dry to yogurt never fully disperses and leaves bitter pockets.
Add the yogurt and vanilla and whisk smooth.
Add the protein powder last and whisk hard for a full minute. It will look too thick at first and then loosen as the powder hydrates; resist adding more liquid during this stage.
If it is still stiffer than pudding after a minute, add almond milk a teaspoon at a time. Most batches need nothing.
Chill at least 30 minutes. It thickens substantially as it rests, which is the difference between this and a thick yogurt bowl.