The first time that Mac Miller and Jon Brion formally met, Miller was already hard at work on what would become 2018’s Swimming, an album that Brion would sign on to produce. “He comes in and he plays five or six things,” Brion tells Apple Music’s Zane Lowe. “There was more hip-hop-leaning stuff, and it was great and funny and personal—the tracks were already pointing someplace interesting. After a couple of those, he goes, ‘I’ve got these other things I’m not sure what to do with.’” Those “other things” were the beginning of Circles, a now posthumous LP that Miller had envisioned as a counterpart to Swimming—one that finds him exploring levels of musicality, melody, and vulnerability he’d only hinted at before. It feels more akin to Harry Nilsson than hip-hop, and the breadth of Brion’s CV (Kanye West, Fiona Apple, Janelle Monáe) made him the perfect collaborator. With the support of Miller’s family, Brion completed Circles based on conversations the two had shared before Miller’s death in September 2018, adding elements of live percussion, strings, and various overdubs. Here, Brion takes us inside the making of some of Circles’ key songs and offers insights on what it was like to work so closely with Miller on something so personal.