Eggy challah

During my recent maternity leave, I became quite an avid challah baker, and even began to experiment with 'exotic' challahs - for example, challahs with apple slices baked into them (it tastes like a strudel - yum).

But here's one I've never seen before. According to Yediot, it is a Moroccan-style challah, and has raw eggs - whole - baked into the top:

Anyone know where the custom comes from?