Cover; simmer on medium heat for 15 min, stirring occasionally. It will thicken near the end of the cook time; stir more frequently at that time to prevent sticking. Season with salt and pepper to taste.
Meanwhile, preheat broiler to high. Cut peppers in half lengthwise; scrape out and discard seeds.
Arrange half the peppers in Multipurpose Steamer; it’s OK if they overlap. Cover; microwave on high until tender, 4 min 30 sec. Stir halfway through cooking. Repeat with remaining pepper halves.
Place peppers on a Sheet Pan or in a large casserole dish. Fill with Bolognese mixture (about 1⁄3 cup per pepper half) and top with cheese. Broil until cheese melts and edges of peppers are crispy, about 5 min. Rotate pan to ensure even cooking. Sprinkle with additional toppings before serving, if desired.
Per serving: Calories 200, Fat 5 g (Saturated 1.5 g, Trans 0 g), Cholesterol 5 mg, Sodium 570 mg, Carbohydrate 25 g (Fibre 7 g, Sugars 6 g), Protein 19 g.