Once defender Ricardo van Rhijn put Ajax 1-0 up within three minutes, PEC Zwolle seemingly faced an impossible task.
Nobody, however, had told the Kiwi who five minutes later put the teams level with a deflection.
Things got even better four minutes later when Thomas smashed home the rebound after a Zwolle free kick had hit the post.
The shell-shocked Ajax stars conceded two more goals in the first half before a fifth Zwolle goal after the break put the icing on the cake.
Thomas told local reporters that many of his family and friends in the Bay of Plenty must have seen the match online because his phone had not stopped beeping.
"Everyone is really happy for me back home. It's been a fantastic first season for me in Zwolle and this has been a great way to finish the year."
The young All White has joined a select group of New Zealanders winning overseas silverware.
The list includes Wynton Rufer winning the German Cup and European Cup Winners Cup with Werder Bremen in the early 1990s and Ryan Nelsen claiming the MLS Cup with DC United exactly 10 years ago.