Preheat the oven to 400°F (200°C). Pat the chicken dry. Put the mustard and mayonnaise in a small bowl, season with salt and pepper, and whisk to combine.
In a medium bowl, combine the panko crumbs, parmesan cheese, paprika, onion powder, Italian seasoning, Kosher salt, and black pepper.
Dip the chicken into the mayo mixture, coating both sides.
Place the chicken in the panko bowl and turn it over to coat the other side, pressing the panko on so the chicken is well covered.
Arrange the chicken on a parchment-lined baking sheet and mist it with olive oil spray.
Bake at 400°F for 15 to 22 minutes, until the internal temperature reaches 165°F.
Let the chicken rest for five minutes before serving. Garnish with 1 tablespoon of freshly chopped parsley and a squeeze of fresh lemon, if you like.