Froth the butter in a pan and let it brown, then remove from the heat. Separate the eggs. Beat egg whites with a pinch of salt until stiff and cover in the fridge. Mix the flour, a pinch of salt and sugar. Mix in the milk, melted butter, sour cream and egg yolks. Cover and leave the dough to soak for 1 hour. Preheat the oven to 60 °. Fold the egg whites into the dough, heat the fat in a non-stick pan. Spoon the batter into the pan and spread it into a round pancake. When it is almost completely firm on the top, turn it and bake until golden brown. Enjoy with maple syrup or jam, if you like.