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 deeper flavor penetration.
03 - If baking, preheat the oven to 400°F and set a wire rack over a lined baking sheet. If pan-frying, heat ½ inch of vegetable oil in a large skillet over medium-high heat until shimmering.
04 - Arrange three shallow dishes: combine the flour, cornstarch, paprika, cayenne pepper, and garlic powder in the first; beat the eggs with milk in the second; toss the panko breadcrumbs with melted butter and lemon zest in the third.
05 - Remove the chicken from the marinade and pat each breast thoroughly with paper towels to remove excess moisture for better crust adhesion.
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 coating on all sides, ensuring full even coverage.
07 - For pan-frying, cook each breaded breast 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, place the coated chicken on the wire rack, spray lightly 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. Arrange on a serving platter, garnish with fresh lemon wedges and chopped parsley.