Boil the cleaned potatoes and, when cool enough to handle, push off the skins. Put the potato flesh through a sieve and weigh out the required amount.
Strip the coarse stems from the sorrel leaves, wash well and cook quickly in
Put the remaining butter around 4 ramekins and put a spoonful of the cooled sorrel in the bottom of each. Add the cottage cheese, the sour cream and chives to the potato. Beat in the egg yolks until the mixture is very smooth, then whip the egg whites stiffly and fold in.
Divide the mixture between the ramekins, sprinkle with the Parmesan and cook for 10 minutes in a hot oven