1. Set 6 cups water to boil. Put 2 tablespoons of the olive oil in the bottom of a medium saucepan and turn the heat to medium. Chop the prosciutto (remove the fat if you must, but remember that it has flavor) into 1⁄4-inch or smaller cubes and add to the oil. Brown, stirring occasionally, for about 5 minutes, while you prepare the garlic, onion, and greens.
2. Peel the garlic and chop it roughly or leave it whole. Peel and chop the onion. Wash and chop the greens into bite-sized pieces.
3. When the prosciutto has browned, add the garlic and cook, stirring occasionally, until it begins to color, about 2 minutes. Add the onion and cook, stirring occasionally, until it becomes translucent, 2 or 3 minutes. Add the greens and stir, then add the 6 cups boiling water. (You can prepare the dish in advance up to this point. Cover and refrigerate for up to 2 days, then reheat before proceeding.) Stir in the pasta and a good sprinkling of salt and pepper; adjust the heat so the mixture simmers.
4. When the pasta is done, taste and add more salt and pepper if necessary. Drizzle with the remaining olive oil and serve.