01 - Bring a large pot of generously salted water to a rolling boil. Add the mafaldine and cook according to package directions until al dente. Before draining, reserve 1/2 cup of the starchy cooking water.
02 - During the last 3–4 minutes of the pasta cooking time, add the broccoli florets directly to the boiling pasta water. Drain the pasta and broccoli together.
03 - In a large skillet over medium heat, warm the olive oil and butter together. Add the minced garlic and chili flakes if using, and sauté for about 1 minute until fragrant, taking care not to let the garlic brown.
04 - Add the lemon zest, lemon juice, blanched broccoli, and drained mafaldine to the skillet. Toss everything together, then sprinkle in the grated Parmesan, stirring gently until a silky, cohesive sauce coats the pasta. If the mixture appears dry, incorporate the reserved pasta water a splash at a time until the desired consistency is reached.
05 - Season with salt and freshly ground black pepper to taste. Remove from the heat and fold in the chopped parsley.
06 - Transfer to warm plates immediately. Garnish with additional Parmesan and a touch more lemon zest if desired. Serve right away.