Miso and butter are one of Japan's best flavour pairings, and they go especially well with mushrooms. Here they melt into a silky sauce that coats thick, chewy udon noodles.
This is the kind of quick noodle dish you'll find in casual Japanese cafes: a bit of soy and mirin for balance, plenty of black pepper, and spring onion and nori on top. It's vegetarian if you skip the bonito flakes.
Frozen udon works best. It cooks in a couple of minutes and has a much better chew than the shelf-stable kind.
