01 - In a mixing bowl, whisk together the lemon juice, lemon zest, olive oil, minced garlic, salt, and black pepper until well combined.
02 - Place the chicken breasts in a large zip-top bag or shallow dish. Pour the marinade over the chicken, seal or cover, and refrigerate for at least 30 minutes or up to 2 hours for optimal flavor penetration.
03 - If baking, preheat the oven to 400°F. If frying, heat ½ inch of vegetable oil in a large heavy-bottomed skillet over medium-high heat until the oil reaches 350°F.
04 - Arrange three shallow dishes side by side: combine the flour, cornstarch, paprika, cayenne, and garlic powder in the first; whisk the eggs and milk together in the second; toss the panko, melted butter, and lemon zest together in the third.
05 - Take the chicken out of the marinade and pat each breast thoroughly dry with paper towels to ensure the coating adheres properly.
06 - Dredge each chicken breast in the seasoned flour mixture, shaking off excess. Dip into the egg wash, allowing any drips to fall away. Press firmly into the panko mixture, ensuring full and even coverage on all sides.
07 - For frying: Carefully lower each coated breast into the hot oil and cook 3 to 5 minutes per side until deep golden brown and the internal temperature reaches 165°F. Transfer to a paper towel-lined plate. For baking: Arrange the coated chicken on a wire rack set over a lined baking sheet, lightly spray with oil, and bake 20 to 25 minutes, flipping halfway through, until crisp and fully cooked.
08 - Allow the chicken to rest for 5 minutes before slicing. Garnish with fresh lemon wedges and chopped parsley. Serve immediately.