Melt butter. Beat eggs and sugar until frothy. Mix in the flour, baking powder and melted butter. Place on a baking tray that has been greased or lined with baking paper and bake at 180 degrees for about 15-20 minutes, until the cake is golden brown. After the baking is done, prick with a fork.
For the cast:
Rub the lemon peel and squeeze the lemons. Melt butter. Mix all ingredients together and distribute evenly on the baked cake while it is still warm.
It tastes best when it has been baked a day in advance and can steep.