In a large bowl, combine the chicken breasts and dill pickle juice. Cover and marinate in the refrigerator for at least 1 hour, or up to overnight for more flavor.

Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it with cooking spray.

In a shallow dish, mix together the breadcrumbs, Parmesan cheese, garlic powder, onion powder, black pepper, and salt.

In another bowl, whisk together the egg and Dijon mustard until well combined.

Remove the chicken from the pickle juice and pat dry with paper towels. Dip each chicken breast into the egg mixture, allowing excess to drip off, then coat thoroughly in the breadcrumb mixture.

Place the coated chicken breasts on the prepared baking sheet. Lightly spray the tops with cooking spray or drizzle with olive oil for extra crispiness.

Bake in the preheated oven for 25-30 minutes, or until the chicken is cooked through and the coating is golden brown. The internal temperature should reach 165°F (75°C).

Let the chicken rest for 5 minutes before slicing and serving.