I was wondering why the serving sizes on challah recipes had a minimum of 2. A number of convenience? Or perhaps its more economical to make 2 loaves at a go. Wrong.
According to Jewish tradition, Sabbath and holiday meals begin with a blessing over four loaves of bread (two Friday night and two Saturday afternoon). This "double loaf" commemorates the manna that fell from the heavens when the Israelites wandered in the desert for 40yrs after the Exodus from Egypt. Manna did not fall on the Sabbath or holidays; instead, a double portion fell before the Sabbath and holidays. Thus, the serving size of 2 is symbolic of this.
Unlike the brioche and other enriched european breads which contain butter or milk, challah is usually parve. Parve is a hebrew term that describes foods which do not contain dairy and/or meat. And if you do ask, yes, eggs go into making challah. But hey guess what, eggs are not dairy products - I just learnt that. So yeah, eggs are allowed in challah.