Preheat your oven to 400°F (200°C). Lightly grease a baking dish large enough to hold the chicken breasts in a single layer.

Pat the boneless skinless chicken breasts dry with paper towels, then place them on a cutting board. If they are very thick, gently pound them to an even thickness for more even cooking.

Drizzle the chicken breasts with the olive oil, then sprinkle both sides with the salt, black pepper, garlic powder, onion powder, and paprika. Rub the seasonings in so the chicken is well coated.

Place the seasoned chicken breasts in the prepared baking dish in a single layer, leaving a little space between each piece.

In a medium bowl, stir together the mayonnaise and grated Parmesan cheese until you have a smooth, thick mixture.

Spoon the mayonnaise and Parmesan mixture evenly over the top of each chicken breast, spreading it gently with the back of the spoon so the top is well covered.

In a separate bowl, combine the panko breadcrumbs and melted unsalted butter, stirring until the breadcrumbs are evenly moistened.

Sprinkle the buttery panko breadcrumbs evenly over the mayonnaise and Parmesan layer on each piece of chicken, pressing very lightly so they adhere.

Sprinkle the shredded mozzarella cheese evenly over the top of the breadcrumb layer on each chicken breast.

Place the baking dish in the preheated oven and bake for 20 to 25 minutes, or until the chicken is cooked through and the top is golden and bubbling. The internal temperature of the chicken should reach 165°F (74°C).

If you would like a deeper golden crust, switch the oven to broil for 1 to 2 minutes at the end of the cooking time, watching closely so the topping does not burn.

Remove the baking dish from the oven and let the LongHorn Steakhouse Parmesan Chicken rest for about 5 minutes so the juices settle and the topping firms slightly.

Sprinkle the chopped fresh parsley over the chicken breasts, if using, then serve the LongHorn Steakhouse Parmesan Chicken warm.