Peel the onion and chop it finely. Wash and peel the mushrooms. Cut them into small pieces.
Heat the oil and saute the onions and mushrooms until softened. Season with salt and black pepper. Add the prepared mixture to the mince and knead until homogeneous.
Beat the eggs. Add the grated cheese and stir. Heat a suitable tray laid out with oiled baking paper. Pour in the egg mixture and spread it out. Bake this egg layer.
Pour the meat filling over the egg layer and spread it out evenly.
Wrap the whole thing into a roll and return it to the tray. Cover the roll with baking paper and bake for 15 min. in a hot oven.