A few people have asked me what IS that challah that was so cursed. :) The short answer: It's a rich egg yeast bread that is usually braided and served at the beginning of the three meals of shabbat (Friday dinner, Saturday lunch, and seudat shlishit (AKA "third meal")).
And now for the long answer, since everything in Judaism is 1,000x more than what is apparent on the surface!
"Challah" does not actually refer to the bread itself, though that is how the word is commonly used. In the torah, we are commanded to separate a small portion from a batch of dough (if it is of a certain size). The part that is separated is called the "challah." In the days of the temple, about 1/24 of every private citizen's batch of dough was set aside as a tithe to go to the priests. The priests in the temple had no income per se, so they lived off of the tithes (money, animals, food, etc.) of the people. Since the temple no longer stands, removing the challah from the dough is now a symbolic act. The removed part is thrown into the fire or carefully discarded.
At the shabbat meals, two loaves are served (although many serve just one loaf for the last meal). This is in memory of the double portions of manna that fell from the heavens and sustained the Jews during their many years of wandering in the desert after leaving Egypt.
Bread, perhaps more than any other food, is full of the spiritual energies that went into making it, from the farmer in the field to the woman baking the challah at home. It is one of the most labor-intensive sources of nourishment there is. Think of all the steps, as traditionally outlined in Judaism: plowing, planting, reaping, gathering, threshing, winnowing, selecting, sifting, grinding, kneading, and baking. And eating! Making bread is no small accomplishment.
In Judaism, the earthly world is the vehicle through which we live a spiritual life. The physical and spiritual worlds are not in opposition to each other, and in fact must act in symbiosis. The physical world is here to be permeated by the spiritual world and made holy. And challah is not merely a good recipe. It takes flour from the earth, representing our physical self, and water from heaven, representing our spiritual self. (Water is often used as a metaphor for torah.) These are united in the dough and eating the bread is elevated to a ritual act at the meal by means of a brachah, a special blessing.
In fact, nearly any action a Jew takes has a blessing, a brachah, that goes with it. For example, every time we have finished going to the bathroom we recite a brachah that thanks Hashem for making the vast numbers of openings and cavities in our body work properly. If even one of these went out of whack, we would become ill. Everything we do can be lifted up into the spiritual world, and that really is one of the primary lessons in Judaism.