Finely chop the almonds.
In a bowl, mix egg whites, protein powder, unsweetened cocoa powder, almond flour, and erythritol.
Add the chopped almonds to the batter and mix evenly.
Line an oven-safe pan with parchment paper and pour in the batter.
Bake in a preheated oven at 180°C (356°F) for 25 minutes.