Boil the pasta. Bring a large pot of salted water to a rolling boil. Add the pasta and cook according to package directions until just shy of al dente. In the last 2 minutes of cooking, add the broccoli florets to the pot. Reserve about 3/4 cup of the starchy pasta water, then drain the pasta and broccoli together.

Season the chicken. Pat the chicken dry with paper towels. Toss with 1 tablespoon olive oil, 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper. If you like heat, sprinkle on the red pepper flakes.

Sear the chicken. Heat a large skillet over medium-high. Add the remaining 1 tablespoon olive oil. When hot, add the chicken in a single layer. Cook without moving for 2–3 minutes to get some color, then stir and cook another 3–4 minutes, until the chicken is cooked through.

Bloom the garlic. Reduce the heat to medium. Push the chicken to one side of the skillet. Add the garlic to the empty side and cook 30–60 seconds, until fragrant. Don’t let it brown.

Create the sauce base. Pour in 1/2 cup chicken broth or reserved pasta water. Scrape up any browned bits from the pan. Simmer 1–2 minutes to let the flavors come together.

Combine everything. Add the drained pasta and broccoli to the skillet. Toss well so the pasta absorbs the sauce. If it looks dry, add more reserved pasta water, a splash at a time, until it’s glossy and lightly sauced.

Finish with zest and cheese. Remove from heat. Stir in the lemon zest, lemon juice, and Parmesan. Taste and adjust seasoning with more salt, pepper, or lemon as needed.

Garnish and serve. Sprinkle with fresh parsley or basil, and add extra Parmesan at the table. Serve warm.