Preheat oven to 425°F. Line a baking sheet with parchment paper and coat with nonstick spray.
In a large bowl, mix ½ cup yogurt, ¼ cup Dijon, and 2 tablespoons honey. Add chicken and let sit at least 15 minutes or up to overnight.
In a shallow dish toss together pecans, breadcrumbs, kosher salt, garlic powder, smoked paprika, and black pepper.
Remove chicken from yogurt mixture, scraping off excess marinade and add to shallow bowl with pecan mixture. Press firmly to adhere pecan mixture, turn breast over and repeat so all sides of the chicken are completely covered.
Transfer coated chicken to prepared baking sheet and repeat process with remaining pieces of chicken. Add remaining pecan mixture to top of chicken and press down even. Coat with cooking spray.
Bake chicken in oven until cooked through, flipping halfway through, about 20-25 minutes total.
Meanwhile, in a small mixing bowl stir together remaining 2 tablespoons Greek yogurt, remaining 2 tablespoons Dijon mustard, and remaining 2 tablespoons honey. Season to taste.
Serve chicken with honey mustard sauce.