Preheat oven to 400 degrees. On a baking sheet, arrange broccoli evenly and drizzle with oil. Sprinkle with ½ teaspoon chili flakes and garlic slices, and roast for 10 minutes until broccoli appears golden at edges and slightly crisp.

While the broccoli cooks, bring a medium pot of water to a boil over medium-high heat, and cook pasta for 8 minutes until al dente. Remove from heat and drain thoroughly.

Add pasta to a serving dish and top with broccoli, remaining chili flakes, and garlic slices. Drizzle with a little extra oil, sprinkle with lemon zest and juice. Mix well. 

Toss once more with salt and pepper and serve with a few lemon slices for squeezing over.