In a bowl, mix protein powder, oat flour, and cocoa powder together.
Add the egg, milk, and honey, then mix until the batter becomes smooth.
Add the baking powder and gently stir to finish the batter.
Pour the batter into an air fryer basket lined with parchment paper or a microwave-safe container.
Bake in the air fryer (170°C for 15 minutes) or microwave (4~5 minutes).
Let it cool before serving.