Place the fat, salt and 150 g sugar in a mixing bowl and mix with the whisks of the hand mixer. Separate 3 eggs. Stir egg yolks and 1 egg one after the other into the fat cream. Mix flour and baking powder and stir in alternately with the lemonade.
Spread the dough evenly into 6 firm paper baking cups. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 30 minutes.
In the meantime, beat the egg whites until stiff, adding 150 g sugar. Pour the beaten egg whites into a piping bag with a perforated spout. Remove muffins from the oven about 5 minutes before the end of the baking time. Spray the beaten egg white onto the muffins and continue baking.
Take the finished muffins out of the oven and let them cool down on a cake rack.