In 10-inch skillet, cook sausage over medium-high heat 3 minutes, stirring to crumble. Add onions and peppers. Cook 5 minutes longer or until sausage is no longer pink and vegetables are tender. Place mixture in large bowl. Add hash browns, 11/2 cups of the cheese, the sour cream and soup; stir to coat. Spoon mixture into casserole. Top with remaining 1/2 cup cheese.