Place the ham in a bowl along with all the other ingredients up to and including the pepper, mix well.
To shape the croissants
Cut the circles of dough into 8 cake-like pieces. Spread the filling evenly on top, leaving a border of approx. 1 cm all the way around. Brush the edges with egg white. Roll up the dough towards the pointed end. Bend the ends of the croissants inwards and crimp. Place the croissants on a baking tray lined with baking paper. Whisk the egg yolk with a little water, brush the croissants with the egg wash.
Approx. 20 mins. in the lower half of an oven preheated to 220°C.