Preheat oven to 400 degrees F. Line a baking sheet with foil and spray with nonstick cooking spray.
Whisk together the Honey Mustard Sauce ingredients in a medium bowl. Remove 1/4 cup Sauce to a small bowl and whisk in one egg (this becomes your “Honey Mustard Egg Wash”). Set aside.
To prepared pan, add potatoes, 1 tablespoon olive oil, 1/4 teaspoon salt, 1/8 teaspoon pepper and 1 tablespoon Honey Mustard Sauce. Toss until evenly coated then spread potatoes out evenly. Bake for 10 minutes at 400 degrees F.
Meanwhile, whisk together Pretzel Coating ingredients in a shallow dish. Pat chicken very dry with paper towels. Dredge chicken in Honey Mustard Egg Wash with one hand, letting excess drip off then dredge in Pretzel Coating with the opposite hand, pressing crumbs firmly into chicken so they stick. Set chicken on oven baking rack to rest if your potatoes aren't out of the oven yet.
Once potatoes have cooked for 10 minutes, stir and push potatoes to one side of pan. Add chicken in a vertical row as pictured and lightly spray with nonstick cooking spray. Bake 12-18 more minutes at 400 degrees F - just until chicken is cooked through. If potatoes aren't done cooking for whatever reason, then remove chicken from pan and continue to cook until potatoes until tender.
Serve chicken with remaining Honey Mustard Sauce.