Melt 1/2 cup of unsalted butter and 4 oz of semi-sweet chocolate in a microwave-safe bowl. Heat in 30-second intervals until smooth, then allow to cool slightly.

In a separate bowl, beat 2 eggs until frothy. Gradually mix in 1/2 cup of sugar until dissolved and fluffy.

Carefully add the cooled chocolate mixture to the egg mixture, stirring until well combined and smooth.

Sift in 1/4 cup of all-purpose flour, 1 pinch of salt, and 1/2 teaspoon of baking powder. Fold gently until just combined.

Preheat air fryer to 375°F (190°C). Grease four 4oz ramekins with butter and fill each about 3/4 full with the batter.

Place the ramekins in the air fryer and cook at 375°F for 7-9 minutes. For a gooey center, aim for 7 minutes.

Carefully remove ramekins after cooking and allow to cool for 2 minutes. Run a knife around the edges, invert onto plates, and serve.