The original command was given to Adam, even before Eve was created.

See what Genesis 2:16-17 says:

> "And the Lord God commanded the man, saying, Of every tree of the garden thou mayest freely eat,
but of the tree of the knowledge of good and evil, thou shalt not eat of it; for in the day that thou eatest thereof thou shalt surely die."

Soon after, in Genesis 2:22, God creates the woman from Adam's rib. In other words, the prohibition was communicated to Adam first — and he had the responsibility to pass this instruction on to Eve.

Later, in Genesis 3, when the serpent speaks to Eve, she already knew the command ("God said: You shall not eat of it, nor shall you touch it..."), which shows that she was informed — probably by Adam.

In summary:

God gave the command directly to Adam.

Eve learned of the command through Adam.

Both, however, were responsible for the disobedience.