Heat 1 tablespoon olive oil in a skillet over medium heat. Stir in the carrots and celery; cook and stir until the vegetables are tender, about 5 minutes.
Stir in ground beef and pancetta, and cook until browned and crumbled; drain off any excess liquid, and return to heat. Add marinara sauce, wine, and red pepper flakes, and simmer for 10 minutes. Stir in cream, half of the Parmesan cheese, and rice. Simmer 5 minutes more, or until most liquid has absorbed.
Place peppers in a shallow baking dish, and fill with beef mixture. Drizzle with remaining olive oil and top with remaining Parmesan cheese.
Bake, uncovered, for 30 minutes in the preheated oven. Serve hot.