Tagliatelle con le Noci (Tagliatelle with Walnuts)

There’s a little magic in this pasta that looks—and even tastes—a bit like tagliatelle alla Bolognese, one of Italy’s most iconic dishes. Like Bolognese, the walnut-based sauce is luxurious, with plenty of fat and only a hint of tomato. You might think it was a modern, vegetarian take on the classic, with nuts standing in for rich beef and pork. But I f…