Meanwhile, heat 2 tablespoons olive oil in skillet over medium heat. Add the garlic and cook about 30 seconds. Add the panko and the fried onions and cook, stirring until lightly toasted, about 3 minutes. Transfer to a plate; wipe out the skillet. Heat the remaining 1 tablespoon oil in the skillet over medium high heat. Add the cauliflower and cook until the edges brown, about 4 minutes. Add the red pepper flakes and toast 30 seconds. Add the reserved pasta water and cook until the liquid is reduced by half and the cauliflower is crisp-tender, about 1 more minute. Add the pasta, onion mixture and Parmesan to the skillet and toss.