Portobello Mushrooms With White Beans and Prosciutto

Name: Portobello Mushrooms With White Beans and Prosciutto
Ingredients: * 4 large portobello mushroom caps, gills removed; * 4teaspoons olive oil, divided; * 2teaspoons balsamic vinegar; * 1/4cup finely chopped shallots; * 2teaspoons finely chopped garlic; * 1teaspoon chopped fresh rosemary; * 1 can (19 oz) cannellini beans, rinsed and drained; * 1/4cup reduced-sodium chicken broth; * 1ounce prosciutto, chopped; * 2tablespoons finely chopped flat-leaf parsley; * 3/4cup baby spinach; * 2tablespoons panko breadcrumbs; * 2tablespoons grated fresh Parmesan; * 1 Olive oil cooking spray