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!