Heat oven to 425°F. Line large cookie sheet with foil; spray with nonstick cooking spray.
Cut each bread piece in half horizontally. Hollow out center of each to form 3/4-inch-thick shell; discard bread crumbs or save for another use. If necessary, cut thin slice off rounded bottom of each piece so it will sit firmly while baking. Place, hollowed side up, on sprayed foil-lined cookie sheet. Set aside.
In large bowl, combine spaghetti sauce, beans, onion, garlic powder and pepper; mix well. Spoon mixture evenly into bread shells, spreading almost to edges. Sprinkle each with cheese and basil.
Bake at 425°F. for 15 minutes or until cheese is melted and filling is hot.