How to Make It
Heat oven to 425° F. Cook the spaghetti according to the package directions; drain and return it to the pot.
Meanwhile, toss the cauliflower and 2 tablespoons of the oil on a rimmed baking sheet. Roast until tender, 25 to 35 minutes.
Heat the remaining 2 tablespoons of oil in a large skillet over medium heat. Add the tomatoes (and their juices), garlic, anchovies, ¾ teaspoon salt, and ½ teaspoon pepper. Cook, stirring occasionally, until thickened, 20 to 25 minutes.
Add the sauce and cauliflower to the pasta and toss to coat.
Serve topped with the ricotta and pine nuts.