Potatoes are first mentioned in a cookbook from the 16th century. During the next 150 years the vegetable was an exotic speciality reserved for the nobility. During the 18th century it became more widespread but it was still not generally considered worth eating.
Generally it was served boiled with butter or cream on it. One recipe from 1766 writes that the “earth-apples” should be washed and peeled, boiled in some salted water for a short time. Afterwards they should be stewed in a deep pan with butter, sweet cream, breadcrumbs, salt and some nutmeg. A favourite side dish for salted herrings, it was a staple in any European household until French-fries were introduced in the late 20th century.
A slightly tastier (French) variation is to chop a couple of onions finely and stir them in hot butter without browning them. Add flour and stew with milk. Taste the white béchamel sauce with salt and nutmeg and pour it in a deep (buttered and crumbled) pan over layers of 8 – 10 sliced, boiled potatoes, 3 hardboiled, sliced eggs and some chopped ham or salted herring, top with grated cheese and bake in oven at a low temperature (160 celcius) for 30 – 40 minutes.
Another French variation from the 18th century is “Flan de pommes de terre Soufflé” or potato soufflé. Cook eight potatoes and mash them with a pestle and mortar. Pound a generous knob of butter with lemon peel or orange flower to flavour. Blend eight egg yolks with a fork and mix well with the mashed potatoes. Beat the egg whites until stiff as if making a sponge cake, then blend into the remainder of the ingredients and cook in an oven (160 celcius for hour). The Soufflé should be sprinkled with sugar. Such a souffle or pie (in German: Cartoffel Torte) was served for Goethe at his 64th birthday party in Ilmenau. At the serving, the hot pie was decorated with a wreath of fresh flowers. Whether Frederick the Great partook of such delicacies is not known.