Mix the butter and an egg together. Add the flour, salt and caraway seeds and knead into a smooth shortcrust pastry. Let the dough rest in the refrigerator for 45 minutes.
For the filling, stir together the crème fraîche, two eggs, mustard, marjoram and chives.
Lay out the prepared dough in a round, 26 or 28 cm large, greased springform pan and form an approx. 2-3 cm wide border.
Raw sausage, I prefer without casing, but any other is also possible, if necessary cut in half lengthways and lay out on the floor. Spread the filling evenly over the top.