Clean and wash spring onions and cut them diagonally into thin rings. Wash and peel the potatoes and cut them into approx. 3 mm thin slices. Heat oil in 3-4 portions in a large coated pan and fry the potatoes in 3-4 portions for about 5 minutes. Lightly season the potatoes with salt, pepper and a little paprika. In the meantime clean and clean the mushrooms and cut them into slices. Heat 1 tablespoon of oil in a pan.
Fry the mushrooms in it until lightly golden brown. Cut the Landjäger into slices. Wash, clean, halve and thinly slice the tomatoes. Grate cheese. Separate eggs. Mix egg yolk and milk and season with salt and pepper. Beat egg white until stiff. Stir egg whites and cheese into the egg yolk milk. Put 1/3 of the mixture on a greased baking tray (25 x 40 cm). Spread potatoes, mushrooms, Landjäger, tomato and spring onions on it. Spread the rest of the egg mixture on top and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 30 minutes.
Mix egg yolk and milk and season with salt and pepper. Beat egg white until stiff. Stir egg whites and cheese into the egg yolk milk. Put 1/3 of the mixture on a greased baking tray (25 x 40 cm). Spread potatoes, mushrooms, Landjäger, tomato and spring onions on it. Spread the rest of the egg mixture on top and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 30 minutes. Wash the chives, dab dry and cut into thin rings. Sprinkle chives on the baked cake and serve