Escarole with Italian Sausage and White Beans

Name: Escarole with Italian Sausage and White Beans
Ingredients: 3 tablespoons olive oil; 12 Italian sausages (about 3 pounds), casings removed; 1 cup chopped onion; 1/2 cup chopped prosciutto (about 2 ounces); 1 tablespoon minced garlic; 1/2 teaspoon dried crushed red pepper; 1 large head escarole, chopped (about 10 cups); 3/4 cup dry white wine; 4 (15-ounce) cans Great Northern beans, rinsed, drained; 1 cup chicken stock or canned low-salt chicken broth; Freshly grated Parmesan cheese (optional)