After you made the pistachio Gremolata from above you will start working on the charred cauliflower! In a large bowl add in the cauliflower florets from the head of the cauliflower. Take the cauliflower floret & cut them in half to where they lay flat on the baking sheet as best as possible.
Then toss the florets in a large mixing bowl with juice from the 1 lemon, olive oil, salt, paprika, garlic powder, chili powder & pepper. Then roast for 18-22 minutes. While they are roasting you will make the pasta & the sauce. Then throw together. Should come together in those 22 minutes the cauliflower is roasting.
In large stock pot cook pasta noodles according to package. Reserve 1/2 cup pasta water & then, rinse & drain then noodles.
In a 5-7 qt sauce pan or dutch oven add 2 cloves minced garlic & 1/2 cup butter. Turn on medium low. When it starts to bubble, turn down to a very low simmer. Let it simmer for 2 minutes. Then pour in the reserved pasta water, lemon juice, half & half & chicken broth. Whisk together, vigorously. Continue whisking until the half & half is incorporated. It may try to start to separate but keep whisking & when we start to simmer it will come together.
Reduce to a medium low & simmer for 5 minutes. Then stir in oregano,salt, basil, chili powder, pepper & lemon zest. Then in a small bowl add in 2 tsp arrow root & 4 tsp warm water, whisk until it becomes a slurry. Then slowly add in the arrow root slurry, until it starts to thicken to your liking.Slowing figure 8 the slurry in. When using arrow root you do not want it to then boil, because it will break apart the thickening components.
Pour in the drained pasta. Stirring in the pasta into the lemon butter sauce. Let it simmer on low for another 5 minutes. Continuing to stir.
When ready to portion out on plate. Put the pasta on the plate, sprinkle with a good portion of pistachio Gremolata, the charred cauliflower & shaved pecorino cheese on top!