Boil the potatoes and purée into a smooth mash.
Add the cream, butter and eggs.
Season to taste with white pepper, salt and the green herb powder.
Transfer to a piping bag and portion into long strips onto a sheet pan.
Freeze and cut into equal pieces.
Roll the purée first in the flour, dip into beaten egg white and bread in the panko.
Fry the croquettes at 180°C in neutral vegetable oil or fat and serve immediately.