PREPARATION:

1. Spray 4- or 6-cup casserole with nonstick cooking spray; set aside.
2. Place potatoes in large saucepan; add water to cover. Bring to a boil over high heat; boil 12 minutes or until potatoes are tender. Drain. Let potatoes stand 10 minutes or until cool enough to handle.
3. Meanwhile, melt margarine in small saucepan over medium heat. Add flour; cook and stir 3 minutes or until small clumps form. Gradually whisk in milk. Cook 8 minutes or until sauce thickens, stirring constantly. Remove saucepan from heat. Stir in nutmeg, paprika and pepper.
4. Preheat oven to 350°F. Cut potatoes into thin slices. Arrange half of potato slices in prepared casserole. Sprinkle with half of onion slices. Repeat layers. Spoon sauce over potato mixture. Combine bread crumbs, finely chopped red onion and cheese in small bowl; sprinkle evenly over sauce.
5. Bake 20, uncovered, minutes. Let stand 5 minutes before serving. Garnish as desired.