24. A few varieties of cake are made light by means of yeast instead of
being leavened with eggs or chemical leavening agents. These cakes are,
of course, similar to bread in many respects, but they are sweeter and
richer than bread and contain eggs. For this reason they are not
economical mixtures and should not be made if economy must be practiced.
Because of the sugar, butter, and eggs used in them, the action of the
yeast is slow; consequently, the processes involved in making these
mixtures are neither short nor simple. Often, after they have been baked
in a mold, the center is removed and the shells are then filled with
different mixtures to make a variety of desserts.