Whisk together yogurt, mustard, garlic, 2 teaspoons of salt and 2 teaspoons of black pepper. Add chicken pieces and turn to coat in marinade. Cover bowl and refrigerate for at least 30 minutes, up to 12 hours.
Preheat oven to 425°F. Line a rimmed baking sheet with foil. Place a wire rack on top of baking sheet and lightly coat with nonstick cooking spray.
Place flour, paprika, thyme, baking powder, remaining 1 teaspoon salt and 1 teaspoon black pepper in a large plastic bag. Remove chicken from marinade, shake off excess and place in flour mixture. Shake to coat, shake off excess coating and place on prepared rack. Repeat with remaining chicken. Discard remaining marinade and seasoned coating.
Lightly coat chicken with cooking spray and bake until golden brown and a digital thermometer reads 160°F, 50-60 minutes.