Chop fresh broccoli into small florets. If using frozen, let it stand out a few minutes, then give it a quick coarse chop and set aside.
Set a large colander in the sink, placing a glass mug in the center. This will help you remember to grab some pasta water before draining!
Bring a large pot of water to a boil. Generously salt the water (I add about 2 teaspoons of salt), then cook the rotini pasta according to package instructions, minus one minute.
Two minutes before the pasta is done, add the chopped broccoli. This will ensure it’s tender but still crisp!
Before draining, use the mug to scoop out a big scoop of pasta water and set it aside. Then, drain the pasta and broccoli together. Don’t rinse them under cool water!
While the pasta is cooking, heat the butter in a large pan that will accommodate all the ingredients. Once melted, add garlic and all seasonings. Season with salt and pepper (I add around 1/4 teaspoon each) and cook until golden, stirring constantly for about 30 seconds.
Pour in 1/2 cup of chicken broth; you should hear it sizzle and boil. Scrape up any browned bits from the pan, letting it evaporate mostly before adding the other 1/2 cup. Stir well.
Add the heavy cream and Parmesan cheese. Stir to mix everything. Simmer over medium heat, stirring occasionally for about 3 to 5 minutes or until the sauce thickens and slightly reduces. Be careful not to let it boil; reduce heat if necessary.
Once you have that thick and creamy sauce, add the drained pasta and broccoli. Use tongs to toss them in the sauce until everything is nicely coated, 1 to 2 minutes. If the sauce is too thick, gradually add in the reserved pasta water until you reach your desired consistency.
Finally, taste and adjust seasoning with more salt or pepper. Add lemon zest if desired for a fresh twist.
Serve immediately, topping individual plates with a touch more Parmesan cheese and fresh parsley. Add red pepper flakes and a squeeze of fresh lemon juice as desired. Enjoy your delicious Broccoli Pasta right away! It’s best when freshly tossed.