How to Make It
Preheat the broiler. Bring a large pot of salted water to a boil. In a medium skillet, heat 1 tablespoon of the olive oil. Add the garlic and cook over moderate heat until lightly golden, about 3 minutes. Add the cream and simmer until thickened slightly, about 2 minutes. Season with salt and pepper.
Cook the rigatoni until al dente; about 6 minutes before the rigatoni is done, add the cauliflower florets to the pot. Drain, reserving 2 tablespoons of the pasta cooking water.
Meanwhile, in a medium bowl, toss the panko with the Parmigiano cheese and the remaining 2 1/2 tablespoons of olive oil; season with salt and pepper.
Return the rigatoni and cauliflower to the pot. Add the garlic cream, the prosciutto and the reserved pasta water and toss until the pasta is coated. Scrape the pasta into a large shallow baking dish and sprinkle the panko mixture evenly over the top. Broil for about 2 minutes, rotating constantly, until the topping is evenly browned. Serve hot.