Mark Gillespie of WhiskyCast is probably mainly known for his whisky related podcasts. However, he also produces videos and I think I probably have shared one or two of his videos before. Recently he published a video about a visit to the Port Ellen Maltings, a place not many get to see, although he kind of picked the wrong day (for reasons explained in the video):
In the video Mark mentions that today only a handful of distilleries do any of their own malting. If memory serves me right there are only about six or seven distilleries left in Scotland who do this, three of them are actually on Islay: Laphroaig, Bowmore and Kilchoman.