Start by bringing a large pot of salted water to a boil. Add the uncooked penne pasta and cook according to package instructions until al dente. In the final 2-3 minutes of cooking, add the broccoli florets to the pot. Drain the pasta and broccoli together, reserving about 1/4 cup of pasta water.
In a large skillet, melt the butter over medium heat. Whisk in the flour and cook for about one minute until it forms a roux. Add the minced garlic and sauté for an additional minute until fragrant.
Gradually pour in the chicken or vegetable broth, stirring constantly to avoid lumps. Then, stir in the heavy cream, lemon juice, and Italian seasoning. Allow the sauce to simmer gently for about 3-4 minutes, thickening slightly.
Add the cooked pasta and broccoli to the skillet, tossing to coat everything evenly in the creamy sauce. If the sauce is too thick, add a splash of the reserved pasta water. Sprinkle in the freshly grated parmesan cheese and stir until melted. Season with salt and pepper to taste.
Serve your Creamy Lemon Broccoli Pasta immediately, garnished with extra parmesan or a sprinkle of fresh herbs if desired.