Potato pie

• 10 large potatoes
• 300 g (10 oz) butter
• 8

Bake the potatoes (do not boil, as the purée should be very dry) and mash carefully with the hot melted butter. Keeping the mixture from cooling down, gradually add 4 beaten eggs, mixing well. In a separate bowl, beat 4 egg yolks with the sugar until the mixture turns white. Combine with the potato mixture. Beat the remaining whites into a stiff foam and add to the egg mixture, whipping briskly