Wash the cauliflower head and cut it into florets. Let them dry on a kitchen towel.
Scatter the cauliflower on a parchment-lined baking tray and drizzle them with olive oil. Season with salt and black pepper.
Place the baking tray in a preheated oven at 425 degrees Fahrenheit for about 30 minutes or until the cauliflower florets are roasted to perfection.
Meanwhile, fill a pot with water and place it over high heat. Season the water with salt.
Once the water starts to boil, add pasta and cook until al dente.
Reserve about a quarter cup of pasta water separately and drain the pasta.
Add butter to a pot and melt it over medium heat.
Once the butter melts, add minced garlic and sauté for a minute or until fragrant.
Pour in a quarter cup of pasta cooking water, lemon zest, and red pepper flakes. Mix well and let the water simmer.
Add about a half cup of grated parmesan cheese and mix well until it melts.
Stir in the cooked pasta and add the roasted cauliflower at the end.
Season with salt and black pepper if it needs more flavor.
Serve the roasted cauliflower pasta with freshly grated parmesan cheese and freshly chopped parsley.
Enjoy!