Remove and discard casings from sausage. Cook sausage in a large skillet, stirring until sausage crumbles and is no longer pink; drain.
Add green onions and next 3 ingredients to skillet. Sauté 4 minutes or until vegetables are tender. Stir in roasted bell peppers. Drain and cool.
Spread 4 cups of bread cubes in a lightly greased 13- x 9-inch baking dish. Top with half each of the sausage mixture and cheese. Repeat with remaining bread, sausage, and cheese.
Whisk together eggs and milk. Pour egg mixture over bread. Cover and chill 8 hours.
Bake, covered, at 325° for 1 hour or until bubbly and hot.