WARNING regarding that site:

"Accuracy

The model of an egg used to derive the above formula involves several approximations. For a more accurate treatment one would need to note that the thermal properties of the white, yolk and shell are all different, and treat the egg as three concentric, ellipsoids with Dirichlet boundary-conditions at the water-shell interface and Neuman boundary-conditions for the shell-white and white-yolk parts. Changes in its thermal properties when the white changes state from sol to gel, and the latent heat associated with this change would also need to be accounted for."

Just so you know that it all might be off by a bit. Second or two anyway.