Cut peppers in half lengthwise; remove seeds and membranes. Cook in boiling water, 5 minutes; drain well. (Or, microwave in 13x9-inch glass baking dish, covered with plastic wrap, 5 minutes on HIGH.)
In large skillet brown ground beef, onion and garlic; drain. Remove from skillet; set aside.
In same skillet, prepare RIce-A-Roni Mix as package directs.
Heat oven to 375 F. Place cooked peppers cut-side-up in 13x9-inch glass baking dish. Combine rice and meat mixture; spoon into pepper halves. Combine tomato paste, water and brown sugar; spoon over rice mixture.
Tent with foil; bake 25 to 30 minutes or until heated through. Sprinkle with cheese, if desired.