At first mix in equal proportions cayenne, sweet biscuit - powder, and hard - boiled yolk of egg. (fieryfoodscentral.com)
Every soufflé begins with a base, explained the general, usually no more than a white sauce of butter, flour and either milk or broth, to which is added the beaten yolks of eggs and whatever material may be chosen to give the soufflé its character, sweet or savory (such as chocolate, fruit purée, spinach, mushrooms, etc.). (si.com)
One example was how bad the yolk of a egg was for you, but was reversed in another study. (religion.blogs.cnn.com)