Cheese in The Netherlands is not vegetarian. There is a product called stremsel which is the stomach of a calf. This is used to keep cheese edible. Jacketz does not use vegetarian cheese so you must choose a potato without. You can still get cheese with vegetarian stremsel most of the time it is available from a health shop or a "natuurwinkel". If a cheese is organic or "biologisch" it is suitable for a vegetarian.
Jacketz had great service and great food. It was brought to yoou quickly and really inexpensive! Around 10 euros for a good potato. Ordering 1/2 a jacketz is the best thing to do because they are very big!
I would definitely recommend trying the hummus and dukkah. It's a great place with a cosy atmosphere!
Cons: No vegetarian cheese, Quite small