Lay each puff pastry sheet flat on a worksurface. Cut each sheet into 4 even squares, resulting in 8 total squares. Cut each square in half, resulting in 16 mini rectangles. Set aside.
Roughly chop the chocolate bars into small chunks. Make sure each chunk isn’t wider or longer than ½ inch, otherwise it will be difficult to roll inside the croissant.
Sprinkle 2-3 pieces of chocolate along a short side of the rectangle. Roll the dough over the chocolate pieces and continue rolling until you reach the other edge of the dough. Brush a little of the egg wash along the edge to seal. This will help the dough to stick together during baking. Ensure the seam is placed on the bottom while cooking. Lightly brush more egg wash over the top. The final shape should look cylindrical. Continue the rolling process until all mini croissants are completed. Note, be careful not to stuff the dough with too much chocolate otherwise it will be difficult to roll.
Preheat the air fryer to 385˚F / 195˚C. Place a few mini croissants in the air fryer basket, careful to not overlap.
Air fry for 11-13 minutes, or until the tops are golden brown, the dough is cooked, and the chocolate is melty. Repeat the process with any remaining croissants. Serve warm or room temperature. Enjoy!