Combine oatmeal and protein powder in a bowl and mix well.
Add baking powder and salt, then mix again.
Mash the banana and add it to the bowl, mixing thoroughly.
Add unsweetened almond milk and erythritol to form a dough.
Fold in dark chocolate chips until well combined.
Line a pan with parchment paper and drop spoonfuls of dough onto it.
Bake at 180°C (356°F) for 12 minutes.