Preheat the oven to 180°C (356°F).
In a bowl, mix the protein powder, almond flour, unsweetened cocoa powder, and baking powder.
In a separate bowl, whisk together eggs, milk, erythritol, and vanilla extract.
Combine the dry and wet ingredients to make the batter.
Divide the batter evenly into muffin molds.
Bake in the preheated oven for 20 minutes.