Stephanie Tarling is an actress and musician born in England and living in LA, working on an EP set to release in 2017. She's also the breathy voice behind the hauntingly beautiful cover of Leslie Bricusse and Anthony Newley's Pure Imagination, the song sung by Gene Wilder in 1971's Willy Wonka and the Chocolate Factory, that Microsoft used to introduce the world to the Surface Studio.
You can find a high quality MP3 version of the Pure Imagination cover by Tarling on her Bandcamp page, where we learned it's actually her first commercial recording. The song itself was rearranged from its original form by composer Nathan Lanier, whose music you might have heard before if you've watched the Halo 4: Forward Onto Dawn web series. He also composed the soundtrack to Microsoft's first Super Bowl commercial in 2014.