Cake of Light is the name of the eucharist

Eucharist

The Eucharist , also called Holy Communion, the Sacrament of the Altar, the Blessed Sacrament, the Lord's Supper, and other names, is a Christian sacrament or ordinance...

ic host found within Thelema

Thelema

Thelema is a religious philosophy that was established, defined and developed by the early 20th century British writer and ceremonial magician, Aleister Crowley. He believed himself to be the prophet of a new age, the Æon of Horus, based upon a religious experience that he had in Egypt in 1904...

, the religion founded by author and occultist Aleister Crowley

Aleister Crowley

Aleister Crowley , born Edward Alexander Crowley, and also known as both Frater Perdurabo and The Great Beast, was an influential English occultist, astrologer, mystic and ceremonial magician, responsible for founding the religious philosophy of Thelema. He was also successful in various other...

 in 1904. It contains honey, oil, and particular bodily fluids for the base ingredients, and is usually cooked in the shape of a small, flat wafer. It appears by name in two important Thelemic rituals: the Gnostic Mass

Gnostic Mass

A Gnostic Mass is a religious Mass administered by a Gnostic church. Several such churches exist, each with its own Gnostic version of the Mass. Some of these are:* Ecclesia Gnostica celebrates a Gnostic traditional Mass called The Gnostic Holy Eucharist...

 and the Mass of the Phoenix

Mass of the Phoenix

The Mass of the Phoenix is a single person ritual within Thelema, a philosophy and religion created and organized by author and occultist Aleister Crowley...

. However, Crowley thought it was important for magicians to perform a eucharistic ritual of some kind daily (from Magick Book 4, Liber ABA

Magick (Book 4)

Magick, Liber ABA, Book 4 is widely considered to be the magnum opus of 20th century occultist Aleister Crowley, the founder of Thelema...

, ch. 20):

A Eucharist of some sort should most assuredly be consummated daily by every magician, and he should regard it as the main sustenance of his magical life. It is of more importance than any other magical ceremony, because it is a complete circle. The whole of the force expended is completely re-absorbed; yet the virtue is that vast gain represented by the abyss between Man and God.

The magician becomes filled with God, fed upon God, intoxicated with God. Little by little his body will become purified by the internal lustration of God; day by day his mortal frame, shedding its earthly elements, will become in very truth the Temple of the Holy Ghost. Day by day matter is replaced by Spirit, the human by the divine; ultimately the change will be complete; God manifest in flesh will be his name.

Symbolism

The meal contains carbohydrate

Carbohydrate

A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...

s, oil for fats, and honey. Cakes of Light have for their symbolism the five elements: meal (Earth), honey (Air), olive oil

Olive oil

Olive oil is an oil obtained from the olive , a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps...

 (Water), Oil of Abramelin (Fire), and wine leavings (Spirit). The Cake of Light can also be identified with the Sun and the sphere of Tiphareth on the Tree of Life

Tree of Life

The tree of life in the Book of Genesis is a tree planted by God in midst of the Garden of Eden , whose fruit gives everlasting life, i.e. immortality. Together with the tree of life, God planted the tree of the knowledge of good and evil . According to some scholars, however, these are in fact...

.

Cakes of Light in The Book of the Law

The name for Crowley's eucharist first appeared in his received sacred text, The Book of the Law

The Book of the Law

Liber AL vel Legis is the central sacred text of Thelema, written by Aleister Crowley in Cairo, Egypt in the year 1904. Its full title is Liber AL vel Legis, sub figura CCXX, as delivered by XCIII=418 to DCLXVI, and it is commonly referred to as The Book of the Law.Liber AL vel Legis contains three...

. The relevant quotes are as follows (from III:23-25):

For perfume mix meal & honey & thick leavings of red wine: then oil of Abramelin and olive oil, and afterward soften & smooth down with rich fresh blood.

The best blood is of the moon, monthly: then the fresh blood of a child, or dropping from the host of heaven: then of enemies; then of the priest or of the worshippers: last of some beast, no matter what.

This burn: of this make cakes & eat unto me. This hath also another use; let it be laid before me, and kept thick with perfumes of your orison: it shall become full of beetles as it were and creeping things sacred unto me.

Some commentators have interpreted this to mean that the "blood" component mentioned in the second portion of this quote may be formed from menstrual blood or semen

Semen

Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...

.