Begin by bringing a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente, usually about 8-10 minutes. Reserve 1 cup of the starchy pasta water before draining.

In a large skillet over medium heat, pour in 2 tablespoons of olive oil. Once hot, add the minced garlic and sauté for about 1 minute until fragrant.

Slowly pour in the heavy cream along with half of the reserved pasta water, stirring gently to combine. Let it simmer for about 2 minutes.

Stir in the fresh broccoli florets and cover the skillet. Cook for about 5 minutes, or until the broccoli turns tender and bright green.

Uncover and stir in the lemon zest and juice, salt, pepper, and optional red pepper flakes to taste. Adjust seasoning as needed.

Add the reserved cooked pasta to the skillet and toss everything together until well-coated in the creamy sauce.

Sprinkle the grated Parmesan cheese over the pasta and gently toss again until the cheese melts into the sauce. Serve hot.