Take a piece of rye bread dough. After it has risen sufficiently roll out quite thin, butter a long cake pan and put in the rolled dough. Brush with melted butter; chop some onions very fine, strew thickly on top of cake, sprinkle with salt, put flakes of butter here and there. Another way is to chop up parsley and use in place of onions. Then called "Petersilien Platz."