Donovan enjoyed a successful three month loan spell at the Toffees in January during the MLS off-season and has been linked with a move back ever since.
The former Bayern and Leverkusen forward also enjoyed a fruitful World Cup, scoring two goals - one of which sent the US through to the last 16 as group winners.
That has seen his reputation enhanced still further, both at home and abroad, but Garber is determined to keep his prized asset in the MLS.
"Landon is, in my view, the greatest player of our generation and an incredibly valuable part of our history but also of our future," said Garber.
"He proved in England last year on loan and he proved in South Africa that he's a world class player and he's also proved that he loves our league and really has accepted the mantle of really being one of the leaders of the sport.
"It is my hope and my expectation that we will have him for the rest of his career because I think the contributions that he makes are invaluable to our future success."