Heat the butter in a pan and fry the mushrooms in it for 5 minutes. Season with salt and pepper. Whisk the eggs with the cream, season with salt and pepper.
Preheat the oven to 200 ° C top and bottom heat. Roll out the puff pastry into a rectangle on the floured work surface and place on the baking sheet lined with baking paper. Form an edge in the process.
Spread the artichokes, mushrooms and feta cubes on the dough base and pour the beaten eggs over them. Sprinkle with the rosemary and bake for about 35 minutes.