Defrost the pastry sheets. Fry vegetables over a high heat for about 4 minutes without defrosting, then continue to fry for 4-6 minutes. Dice ham. Grate cheese
Place the dough plates on top of each other and roll out round (approx. 30 cm Ø) on the tray. Put vegetables, ham and half of the cheese on one half of the dough. Separate the egg. Brush edges of dough with egg white, fold free dough half over.
Press down firmly. Mix egg yolk and milk, brush dough with it. Sprinkle with rest of cheese. Bake in the preheated oven (electric cooker: 250 °C/circulating air: 225 °C/gas: level 5) for 15-20 minutes