Defrost the dough plates. Heat 1 tablespoon of fat and sauté the flour in it until golden brown. Deglaze with stock and milk and bring everything to the boil. Season with salt, pepper and lemon juice.
Spinach wash, read out. Peel and chop the onion and sauté in the remaining fat. Add spinach and steam for about 5 minutes. Season with salt and nutmeg. Drain the vegetables. Wash fish, cut off skin and dice.
Place the dough sheets on top of each other and roll out thinly. Cut out 8 circles (approx. 14 cm Ø). Grease 4 moulds and sprinkle with breadcrumbs. Put 4 pastry sheets in. Spread spinach, salmon cubes and sauce on top.
Separate the egg. Brush the edges of the dough with egg white. Place the rest of the pastry sheets on top and cut them crosswise. Fold the corners outwards. Spread the surface of the dough with egg yolk. Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for 20-25 minutes until golden brown.