1. Preheat oven to 400°. Place bread in a food processor; pulse 10 times or until coarse crumbs form. Spread breadcrumbs in a single layer on a shallow baking pan lined with parchment paper. Bake in middle of oven until one shade darker (about 5 minutes), stirring once. Using parchment paper, pour breadcrumbs into a shallow bowl to cool. Reline baking pan with paper, and lightly coat paper with cooking spray; set aside to use for chicken. Once breadcrumbs are cool, add Parmesan, salt, pepper, paprika, and garlic powder.
2. Combine yogurt, egg whites, and mustard in a shallow bowl, whisking well; set aside.
3. Pat chicken dry. Dip chicken into yogurt mixture to coat, letting some excess drip off; coat both sides of chicken in breadcrumb mixture, patting to adhere.
4. Arrange coated chicken in a single layer on prepared baking pan; lightly coat tops of chicken with cooking spray. Bake in middle of oven until cooked through (35-40 minutes). Arrange on a platter with lemon wedges and parsley.