Preheat the oven to 180°C (356°F).
In a bowl, mix protein powder, cocoa powder, and baking powder together.
Mash the banana and add it to the bowl along with eggs and almond milk, then mix well.
Once all the ingredients are combined evenly, pour the batter into a lightly oiled baking pan.
Bake in the preheated oven for 20 minutes.