01 - Preheat oven to 400°F. Line a baking sheet with parchment paper or lightly grease it.
02 - Place chicken breasts between two sheets of plastic wrap and pound to an even thickness of about 3/4 inch using a meat mallet.
03 - Sprinkle both sides of each chicken breast evenly with garlic powder, onion powder, paprika, salt, and black pepper.
04 - Arrange three shallow bowls: place flour in the first, beat eggs with milk in the second, and combine panko breadcrumbs with Parmesan cheese in the third.
05 - Coat each seasoned chicken breast in flour, dip into the egg mixture, then press firmly into the panko-Parmesan blend, ensuring full even coverage on all sides.
06 - Heat a thin layer of oil in a large skillet over medium-high heat. Sear the breaded chicken for 2 to 3 minutes per side until golden brown.
07 - Transfer the seared chicken to the prepared baking sheet and bake for 15 to 20 minutes, until the internal temperature reaches 165°F.
08 - While the chicken bakes, stir together ranch dressing, Parmesan cheese, and chopped parsley in a small bowl until well combined.
09 - Remove chicken from the oven and spoon the ranch Parmesan sauce evenly over each breast. Sprinkle shredded Monterey Jack and Parmesan cheese on top.
10 - Return the chicken to the oven and broil for 2 to 3 minutes until the cheese is fully melted and bubbly. Serve hot, garnished with extra parsley if desired.