- Grease and line a 6 inch cake tin. If you’re using a silicone mould you can omit this step. 
- Add the butter, white sugar, brown sugar and cocoa powder to a bowl and microwave for 30 seconds. 
- Mix well and return to the microwave for another 30 seconds. The butter will be completely melted and the mix will be hot. Whisk well until it cools down slightly. 
- Turn your air fryer on and set the temperature to 160c. 
- Add the vanilla and salt and whisk well. 
- Add a room temperature egg and whisk until the mix becomes glossy.  
- Add the flour to the bowl and using a silicone spatula, fold until you don’t see any streaks of flour.  
- Transfer the batter to your cake tin or mould and place it in the air fryer.  
- Air fry for 8-10 minutes or until a toothpick inserted into the centre comes out with only a few crumbs.  
- Cool completely before slicing. 
- Top with salted caramel, chocolate sauce, sprinkles or ice cream and enjoy!