My 3yo wanted purple mash potatoes, it didn’t really work because I used yellow potatoes. Then my 3yo decided she didn’t want potatoes so my wife and I were stuck eating prison gruel.
They turn up in fingerling medleys quite a bit in the us and are great roasted too. https://www.hollandbulbfarms.com/spring-planting-bulbs/vegetables/fingerling-potatoes/magic-molly-organic-fingerling-potatoes