Heat olive oil in a large saucepan and saute the mushrooms, sprinkling with some salt and pepper, in batches until the moisture has evaporated and the mushrooms have taken on a deeper color. Remove the mushrooms from the pan and turn down the heat. Add the rosemary, garlic and onions and cook slowly until very deeply caramelized, taking care to scrape up the browned bits without letting them burn. Return the mushrooms to the pan and pour in the wine. Cook until the pan is nearly dry, and then add enough chicken broth or water to cover. Continue cooking until the pan is nearly dry again.
Cook the cavatelli to al dente in salted boiling water. Add a generous spoonful of mushroom ragu to a saucepan with 1 or 2 ladlefuls of broth or water and bring to a boil. Stir the cavatelli directly into the sauce, working in batches if needed, and let simmer another 3 minutes, adding more liquid if necessary. Stir in a knob of butter, and then season with salt and pepper. Stir in the marjoram, parsley and a bit of blackberry vinegar. Serve immediately in warmed bowls with grated Parmigiano-Reggiano.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.