Prepare the cocottes/ramekins by rubbing them with butter and sprinkle some flour or cacao powder in them. Set aside.
Melt the chocolate and butter together over bain-marie or in a microwave at 30 seconds intervals.
In a bowl with a hand mixer whisk together the eggs, sugar and salt until they are all nice and pale.
To the bowl add the melted chocolate and butter. Once combined, add the flour and mix until all the flour is folded in.
Bake the lava cakes in the air fryer at 180°C/ 350°F for 7 minutes. If you want a less molten centre leave them for 9 minutes.
Take out the lava cakes from the air fryer with a clean towel. Let cool for a minute and gently push in a butter knife around the edges of the ramekin so to loosen the side. Transfer the cakes to a plate and dust with icing sugar.