This article originally appeared on InStyle U.S.
The Goop founder also shared that all the 11-year-old's "birthday wishes came true" as he was gifted a set of cool new fidget spinners before spending a sun-filled day at Legoland in California with friends and his proud mama.
"Birthday happiness," the Shakespeare in Love actress wrote alongside a candid shot, taken from behind, which shows the pre-teen and two of his friends in the popular theme park.
And because it's Gwyneth, traditional theme park fare was out of the question as the health devotee found a healthier snack to her liking.
"Tofu Bao Bun at #legoland was 100. Who knew??" the star captioned a photo of the health-conscious menu item.
While we have yet to see how Martin surprised the 11-year-old for his special day, something tells us it'll also be one for the books