01 - Bring a large pot of generously salted water to a rolling boil. Add the mafaldine and cook according to the package directions, but subtract 2 minutes from the recommended time so the pasta finishes al dente.
02 - Three minutes before the pasta is finished cooking, add the broccoli florets directly to the pasta pot. Reserve 1/2 cup of the starchy cooking water, then drain the pasta and broccoli together.
03 - While the pasta cooks, warm the olive oil in a large skillet over medium heat. Add the sliced garlic and chili flakes if using, and sauté for 1 to 2 minutes until fragrant and just beginning to soften, taking care not to let the garlic brown.
04 - Transfer the drained mafaldine and broccoli into the skillet with the aromatics. Pour in the lemon juice and scatter the zest over the top. Add a splash of the reserved pasta water and toss vigorously to coat, incorporating more cooking water as needed to build a smooth, silky sauce.
05 - Sprinkle the grated Parmesan over the pasta and toss until the cheese melts into the sauce and clings to every ribbon. Season with salt and freshly ground black pepper to taste.
06 - Divide among warm bowls immediately. Finish with an extra shower of Parmesan and a scattering of fresh basil or parsley if desired.