HEAT oven to 350ºF.
HEAT nonstick skillet on medium heat. Add onions; cook 8 to 10 min. or until tender and golden brown, stirring frequently. Remove from skillet; set aside.
ADD sausage to skillet; cook 5 min. or until browned, stirring occasionally. Stir in red pepper; cook 1 min. Add spinach. Cover; cook 2 min. Stir in cheese. Spoon into 9-inch pie plate; top with onions.
BAKE 10 min. Serve with bread.