The long-awaited DLC has an appropriately named island.
http://www.nintendoworldreport.com/news/59109/cuphead-to-serve-its-delicious-last-course-in-late-june
The Delicious Last Course needs a bit more time in the kitchen, and now we know how much.
Studio MDHR have finally announced a release date for Cuphead's "Delicious Last Course" (DLC), and the adventure will resume on June 30, 2022. In addition to a "DLC Island", a new playable character Ms. Chalice will be added.
The trailer can be found below: