Spaghetti with Broccoli-Miso Sauce and Toasted Walnuts

Frozen broccoli, simmered until tender and pureed until smooth with blanched garlic and miso—yes, miso—becomes a creamy, elegant sauce for al dente pasta. Parmesan (or pecorino) cheese and toasted walnuts bring additional umami to the dish, for rich, full, complex flavor, while fresh, bright lemon zest and juice brighten up the flavors. Frozen broccoli is sold as either florets or “cuts” (a mix of florets and stalks); either works in this recipe.