01 - Bring a large pot of generously salted water to a rolling boil. Add the mafaldine pasta and cook according to package instructions until al dente. Reserve 1/2 cup of pasta cooking water before draining.
02 - During the last 3–4 minutes of pasta cooking, add the broccoli florets to the boiling pasta water to blanch them until crisp-tender. Drain the pasta and broccoli together.
03 - In a large skillet over medium heat, warm the olive oil and butter until melted. Add the minced garlic and chili flakes if using, sautéing for about 1 minute until fragrant but not browned.
04 - Add the lemon zest, lemon juice, blanched broccoli, and drained mafaldine to the skillet. Toss thoroughly to combine, then sprinkle in the grated Parmesan, stirring until a silky sauce coats the pasta. If the mixture seems dry, add reserved cooking water a splash at a time to reach the desired consistency.
05 - Season with salt and freshly ground black pepper to taste. Remove from heat and fold in the chopped parsley.
06 - Transfer to warm serving plates immediately. Garnish with additional grated Parmesan and lemon zest if desired.