Taphuis (the restaurant inside of the Lanzerac hotel), has a labeled menu and many gluten free options. It also has a dedicated vegan meals. The menu lists GF options for small plates, mains, and desserts. My meal there was fabulous and I did not have issues after eating.
I do not have celiacs, so I am not sure about possibility of cross-contamination - but this place is in a 5 star hotel and my assumption is that they do their best to accommodate dietary needs.
— Gluten-free items are marked on the main menu