Peel the potatoes and cut them into very thin (!) Slices. Dice the onion very finely. Grease the baking dish with butter, spread a layer of potatoes. Sprinkle onions on top and distribute half of the salmon. To repeat. On top of that again potatoes. Whisk the cream with the spices and pour over. Then sprinkle with cheese and bake for about 1 hour. Sprinkle with the parsley after baking.