Preheat oven to 350°.
Cut tops off bell peppers; discard tops, seeds and membranes. Cook peppers in boiling water 5 minutes; drain and set aside.
Heat oil in a large nonstick skillet over medium-high heat. Add green onions and garlic; sauté 2 minutes. Stir in spinach; cook 1 minute or until spinach wilts. Remove from heat, and set aside.
Place broth and 1/2 cup beans in a food processor or blender, and process until smooth. Stir bean purée into spinach mixture. Add remaining beans, feta cheese, tomato sprinkles, olives, vinegar, and Italian seasoning; stir well.
Divide bean mixture evenly between peppers. Combine breadcrumbs and Parmesan cheese; sprinkle evenly over bean mixture. Place stuffed peppers in an 8-inch square baking dish; bake at 350° for 25 minutes.