1Heat oven to 425°F. Spray rectangular pan, 13x9x2 inches, with cooking spray.
2In shallow dish, stir together potatoes (dry) and red pepper. In another shallow dish, beat egg with fork or wire whisk until foamy; stir in buttermilk.
3Dip chicken pieces into egg mixture, then roll in potato mixture to coat. Place in pan skin side down. Drizzle with butter. Discard any leftover potato and egg mixtures.
4Bake uncovered 30 minutes. Turn chicken; bake 20 to 25 minutes longer or until coating is golden brown and juice of chicken is clear when thickest pieces are cut to bone (170°F for breasts; 180°F for thighs and legs).