This Seeking Tech video guide will show you how to complete the Cake Door side quest in the Verso’s Drafts location of Clair Obscur: Expedition 33.
To open this door, you need to find three pieces of cake, which you get as rewards by completing three other quest in the location. Once you find all pieces, return to the same door to open a new area.
You can find the video walkthrough, with time stamps, below: