Remove all fat from chicken breasts and butterfly it in half to end up with 4 thin pieces. Season both sides with paprika, onion powder, garlic powder, salt and pepper.

Pour the buttermilk in a shallow baking dish, add the mustard, season with salt and pepper and whisk until well combined. Place the chicken in the buttermilk making sure it is well covered. Cover with plastic wrap and refrigerate for 30 minutes.

Preheat oven to 350ºF (180ºC) and place a wire wrack on a baking sheet. Lightly spray the wire rack with oil.

Place the panko bread crumbs in a shallow baking dish and season with salt. Remove the chicken from the buttermilk and dredge each piece in the breadcrumbs. Put the chicken on the wire rack and bake for 20-25 minutes or until chicken is cooked through.