Heat oven to 425°F. Set rack over rimmed sheet; brush with 1 teaspoon oil.
Pat thighs dry; toss with buttermilk. Mix panko, Parmesan, herbs, garlic powder, onion powder, salt, pepper, and remaining 2 teaspoons oil in shallow dish.
Lift thighs from buttermilk, dripping excess into bowl; press both sides into crumbs. Discard leftover buttermilk and crumbs touching raw chicken.
Arrange unfolded thighs on rack. Bake 25 to 30 minutes until coating golden and thickest meat at least 165°F.
Rest on rack 5 minutes; lift with thin spatula and serve.