Bring a large pot of water to a boil. Add the cauliflower and cook until just tender, about 3 minutes. Scoop out the cauliflower, cool in ice-cold water, drain well, and set on plate.
Add the rotini to the pot of boiling water and cook until tender, about 8 minutes.
Meanwhile, heat the oil in a very large, wide skillet set over medium, medium-high heat. Add the cauliflower, kale, proscuitto, garlic, oregano and chilies and cook and stir 3 to 4 minutes, until the kale is tender and cauliflower lightly coloured. Add the stock and bring to a simmer.
When the pasta is cooked, reserve ½ cup of its cooking liquid, then drain well. Add the pasta and reserved cooking liquid and cheese to the skillet, toss to combine, and serve.
Note: Baby kale is sold in tubs in our Produce Department.