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 resealable plastic bag or shallow dish. Pour the marinade over the chicken, seal, and refrigerate for at least 30 minutes or up to 2 hours for optimal flavor penetration.
03 - Arrange three shallow dishes: combine the flour, cornstarch, paprika, cayenne, and garlic powder in the first; beat the eggs with milk in the second; toss the panko with melted butter and lemon zest in the third.
04 - If baking, preheat the oven to 400°F and line a baking sheet with parchment paper, placing a wire rack on top. If frying, heat 1/2 inch of vegetable oil in a large skillet over medium-high heat.
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 an even, full coating on all sides.
07 - For frying: cook each piece 3 to 5 minutes per side until deeply golden and the internal temperature reaches 165°F. Transfer to a paper towel-lined plate. For baking: arrange on the wire rack, lightly spray with oil, and bake 20 to 25 minutes, flipping halfway through, until the crust is crisp and the chicken is cooked through.
08 - Allow the chicken to rest for 5 minutes before slicing. Garnish with fresh lemon wedges and chopped parsley. Serve immediately.