Info from our supplier:
Blown by hand. They are all blown with one hole in the bottom end of the egg (approx 7mm hole). After the hole is drilled the yoke is mushed up with a bit of wire then it is blown out the same hole with a bike pump. After the contents are all blown out all eggs have disinfectant sprayed into them and shaken around to clean all the leftover contents out of the egg. They are then blown out and washed and ready for sale.
Supplier is licensed and license number is included with your egg.