Pierce potatoes with fork. Microwave on high 11 or 13 minutes or until tender, rotating ¼ turn after 6 minutes. Let stand 5 minutes.

Meanwhile in large skillet, brown ground beef over medium high heat until no longer pink, breaking into ¾ inch crumbles. Pour off drippings. Stir in chili powder, ½ teaspoon salt, beans and 1 cup cheese; cook and stir until heated through.

Cut a slit lengthwise in potatoes; fluff pulp with fork. Season potatoes with salt and pepper, if desired. Spoon equal amounts of beef mixture over each potato. Top with remaining cheese and onions.