Heat oil in a heavy large pot over medium-high heat. Working in batches, saute sausage until cooked through, breaking up with back of spoon, about 6 minutes per batch. Using a slotted spoon, transfer sausage to bowl, leaving drippings in pot. Reduce heat to medium; add onion to pot and saute until translucent, about 5 minutes.
Add prosciutto and saute 1 minute. Mix in garlic and crushed red pepper. Add escarole and saute until wilted, about 2 minutes. Add wine and cook 2 minutes. Add beans, stock, and sausage and simmer 10 minutes to blend flavors.
Season to taste with salt and pepper. Transfer to a large bowl. Top with grated Parmesan cheese, if desired.