Break the chocolate bars into pieces. Combine chocolate and butter in a microwave-safe bowl and heat at half power for about 1 1/2 minutes, stirring about every 30 seconds, until smooth. Or use double boiler method on the stovetop, if preferred.
Add salt, powdered sugar, and flour. Stir until well combine. Mixture will be very thick, like cookie dough.
Add eggs and egg yolks and whisk until well combined. Batter will be fudgy and thick, but pourable.
Divide batter evenly among ramekins. Place as many as fit in your air fryer into the air fryer basket.
Cook at 400˚F/204˚C in the air fryer for about 8-10 minutes. 8 minutes for more runny center and 10 for thicker. Top of cakes will look cakey with cracks and darker edges. Allow to set for 2 minutes. The ramekins will be hot!
Run a knife around edged to loosen cakes. Invert onto a plate and tap the bottom of ramekin to help release cake. May need to gently wiggle it a little too. Don't skip the tapping or part of your cake may stick to the ramekin.
Serve warm garnished with powdered sugar, berries, whipped cream, or ice cream.
If using salted butter, decrease salt to 1/4 teaspoon (1.25 ml)