According to Greek myth, who/what nursed the infant Zeus?

Cronus sired several children by Rhea: Hestia, Demeter, Hera, Hades, and Poseidon, but swallowed them all as soon as they were born, since he had learned from Gaia and Uranus that he was destined to be overthrown by his son as he had previously overthrown Uranus, his own father, an oracle that Rhea heard and wished to avert.

When Zeus was about to be born, Rhea sought Gaia to devise a plan to save him, so that Cronus would get his retribution for his acts against Uranus and his own children. Rhea gave birth to Zeus in Crete, handing Cronus a rock wrapped in swaddling clothes, which he promptly swallowed.

Rhea hid Zeus in a cave on Mount Ida in Crete.

AMALTHEIA (Amalthea) was the she-goat nurse of the god Zeus who nourished him with milk in a cave on Mount Dikte (Dicte) in Krete (Crete). When the god reached maturity he created his thunder-shield (the aigis) from her hide and the horn of plenty (cornucopia or keras amaltheias) from her crown.

The Dictaean cave is famous in Greek mythology as the place where Amalthea nurtured the infant Zeus with her goat's milk.

In Greek mythology, Amalthea or Amaltheia is the most-frequently mentioned foster-mother of Zeus.