The midfielder arrived from Ajax with high expectations after captaining the then-Dutch champions at the age of just 24.
Despite the £23.6 million fee that was paid for the Dutchman, he failed to impress for the 'Toffees' and made just 7 appearances in the Premier League during the 2017-18 season.
The player was given the option to move on loan to Napoli in January by the club, but rejected it in favour of hoping to fight for his place. That did not happen, and it now seems certain that Klaassen will leave Goodison Park before the end of the transfer window.
According to 'Sky Sports', the most likely suitors for the player are German outfit Werder Bremen are lining up a permanent deal that would see him sign a four-year deal with the club.
The 'Liverpool Echo' report that the club will lose out significantly on their investment, only managing to recoup around £12 million.
He has already played in the team's preseaon preparations but is likely to complete the move to Germany shortly.