Potato Gratin with Julienne of Mushrooms and Comté Cheese

I’m especially fond of this potato gratin since it employs two of my favorite ingredients: mushrooms and cheese. For depth of flavor I use a mix of fresh meaty oyster mushrooms and dried morels, which contribute a lovely smoky undertone. Mildly sweet and slightly nutty, Comté cheese is the first choice for this dish, but Gruyère makes a fine substitute. The cheese is shredded and mixed into the milk with the mushrooms and just a little cream to produce a lovely sauce with no added flour. Th