Preheat the oven to 400°F / 200°C and lightly grease a baking dish with olive oil.
Mix mayonnaise and ranch seasoning in a small bowl to create the creamy ranch topping.
Combine Parmesan cheese, panko breadcrumbs, and garlic powder in another bowl for the crust mixture.
Place chicken breasts in the baking dish, spread the ranch mixture evenly over each piece, then press the Parmesan crust mixture on top.
Bake for 22 to 25 minutes until the crust is golden brown and the chicken reaches 165°F / 74°C at the thickest part.
Rest for 3 minutes before serving to let the juices redistribute and the crust set.