Step 1: Preheat your oven to 400°F (200°C).
Step 2: Place each chicken breast between two pieces of plastic wrap and pound to an even 1/2-inch thickness. Season both sides generously with salt and pepper.
Step 3: In a small bowl, combine mayonnaise, sour cream, ranch seasoning mix, minced garlic, onion powder, and black pepper. Stir until the mixture is smooth and well combined.
Step 4: In a separate shallow dish, combine the freshly grated Parmesan cheese and panko breadcrumbs, mixing them well.
Step 5: Heat olive oil in a large oven-safe skillet over medium-high heat. Once hot, add the seasoned chicken breasts and sear for 2-3 minutes per side, until lightly golden brown.
Step 6: Remove the skillet from heat. Evenly spread the prepared ranch mixture over the top of each seared chicken breast.
Step 7: Carefully press the Parmesan-panko mixture firmly onto the ranch-coated chicken breasts, ensuring a good, even coating.
Step 8: Transfer the skillet to the preheated oven and bake for 15-20 minutes, or until the internal temperature of the chicken reaches 165°F (74°C) and the crust is golden brown and crispy.
Step 9: Remove from the oven and serve immediately with your favorite steakhouse sides.