"Hungering Cold" does not trigger "Chilblains" skill.
I don't understand why "Hungering Cold"...
Purges the earth around the Death Knight of all heat. Enemies within 10 yards are trapped in ice, preventing them from performing any action for 10 s and infecting them with Frost Fever. Enemies are considered Frozen, but any damage other than diseases will break the ice.
... does not trigger "Chilblains" from the frost talent tree.
Victims of your Frost Fever disease are Chilled, reducing movement speed by 30% for 10sec.
"Icy Touch" and "Chains of Ice" does apply Frost Fever just like "Hungering Cold" and both apply "Chilblains" on the target when "Hungering Cold" doesn't. It just doesn't make sense.