How to Make It
Place a baking sheet in oven. Preheat oven to 450°F (leave pan in oven as it heats).
Cut broccoli into florets. Peel and thinly slice stems. Toss together broccoli and 2 tablespoons oil in a bowl. Arrange broccoli in a single layer on hot baking sheet; arrange lemon slices around broccoli. Bake at 450°F until browned and crisp-tender, about 15 minutes.
Meanwhile, fill a Dutch oven with water; bring to a boil. Add pasta; cook according to package directions for al dente. Reserve 1/2 cup cooking liquid. Drain.
Melt butter in Dutch oven over medium-high. Cook until browned and very fragrant, about 3 minutes. Add remaining 2 tablespoons oil, garlic, and red pepper; cook, stirring constantly, 30 seconds. Stir in pasta, salt, and black pepper. Gently stir in broccoli. Stir in 1/4 to 1/2 cup reserved cooking liquid to reach desired consistency. Top with zest and cheese.