Bucatini with Cauliflower, Capers, and Lemon

Heat broiler with rack 8 inches from heating element. Combine pasta, 5 cups water, 2 tablespoons oil, oregano sprig, pepper flakes, and 2 teaspoons salt in a large, straight-sided ovenproof skillet. Bring to a boil over medium-high heat; continue cooking, stirring occasionally, until sauce is mostly reduced and pasta is al dente, about 8 minutes. Remove from heat; stir in lemon zest and juice.

In a bowl, toss cauliflower with remaining 2 tablespoons oil and 1/2 teaspoon salt, capers, Parmesan, and oregano leaves. Sprinkle over pasta in skillet. Broil until cauliflower is golden in spots and pasta is heated through, about 5 minutes. Toss to combine. Serve with more cheese and pepper flakes, a drizzle of oil, and lemon wedges.