For the puff pastry mushroom tart, remove puff pastry from refrigerator about 10 minutes before processing and preheat oven to 200°C. Heat sunflower oil and sauté young onion together with mushrooms. Add ham and tomatoes and fry briefly. Season with salt, ground pepper, nutmeg, caraway and marjoram.
Line a springform pan with a diameter of about 30 cm with the unrolled puff pastry, forming a 2 cm high rim and spreading the finished mixture on the puff pastry. Mix yolks with crème fraîche and grated cheese, season with salt and pepper and pour over the ingredients. Decorate the surface with strips of pastry, brush with beaten egg. Bake in the oven for about 35 – 40 minutes on the bottom rack until crispy.