1Grease two ceramic ramekins (about 150 ml each) with softened butter, then dust with cocoa powder, tapping lightly to remove excess.
2Melt the dark chocolate and 30 g of butter together in a heatproof bowl, either over a bain-marie or in the microwave in 20-30 second intervals. Stir until smooth and let cool slightly.
3In a separate bowl, beat the egg and egg yolk with the sugar using a mixer or whisk for 2-3 minutes, until the mixture becomes frothy, light in color, and has doubled in volume.
4Fold the melted chocolate mixture into the egg mixture, stirring gently with a spatula using slow, bottom-to-top motions until combined.
5Sift the flour and cocoa powder over the mixture and fold them in gently with wide bottom-to-top motions until no traces of flour remain. Do not overmix.
6Pour half the batter into each ramekin, place one soft caramel candy in the center of each, then cover with the remaining batter.
7Preheat the air fryer to 200°C (400°F) for 3-5 minutes.
8Place the ramekins in the air fryer basket and cook for 8-10 minutes, until the edges are firm and the center still jiggles slightly - a sign that the caramel lava is melted and flowing.
9Remove the ramekins and let them cool for exactly 1 minute. Run a thin knife around the edges, invert the cakes onto plates, and serve immediately before the center sets. Do not overcook!