Preheat oven to 400°.
Combine first 3 ingredients in a shallow dish. Place panko in a shallow dish. Dip chicken, one piece at a time, into buttermilk mixture; dredge in panko.
Place chicken on a baking sheet lined with parchment paper. Lightly coat chicken with cooking spray. Bake at 400° for 40 minutes or until done, turning after 20 minutes.