01 - In a mixing bowl, whisk together the lemon juice, lemon zest, olive oil, minced garlic, salt, and black pepper until well combined. Place the chicken breasts in a resealable plastic bag or shallow dish, pour the marinade over them, seal securely, and refrigerate for at least 30 minutes or up to 2 hours for optimal flavor penetration.
02 - 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 ½ inch of vegetable oil in a large heavy-bottomed skillet over medium-high heat until the oil reaches 350°F.
03 - Arrange three shallow dishes in a row: combine the flour, cornstarch, paprika, cayenne pepper, and garlic powder in the first; whisk the eggs with the milk in the second; and toss the panko breadcrumbs with the melted butter and lemon zest in the third.
04 - Take the chicken breasts out of the marinade and pat them thoroughly dry with paper towels to ensure the breading adheres properly.
05 - Dredge each chicken breast in the seasoned flour mixture, shaking off any excess. Dip into the egg wash, allowing the extra to drip off, then press firmly into the panko mixture on all sides to create a complete, even coating.
06 - For frying, carefully lower each breaded 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 the wire rack, spray lightly with oil, and bake 20 to 25 minutes, flipping once halfway through, until crisp and cooked through.
07 - Allow the chicken to rest for 5 minutes before slicing to retain its juices. Serve garnished with fresh lemon wedges and a generous sprinkle of chopped parsley.