Step 1

Heat the oven. Arrange a rack in the middle of the oven and heat the oven to 375°F.

Step 2

Toast the panko. Spread 1 1/2 cups panko into a thin, even layer on a rimmed baking sheet. Bake until golden-brown, about 7 to 8 minutes. You can do this while the oven preheats, but they may need more time to toast. Set aside to cool while you prep the chicken.

Step 3

Prep the chicken. Trim and discard any large pieces of fat from 2 pounds boneless, skinless chicken breasts. Place 1 chicken breast in a gallon-sized zip-top bag and pound with a rolling pin or the flat side of a meat mallet to an even 1/2-inch thickness. Set aside and repeat with the remaining breasts.

Step 4

Grate the cheese and set up the breading station. Finely grate 1 ounce Parmesan cheese (1/2 cup) and place in a wide, shallow bowl. Add the toasted panko (reserve the baking sheet) and 2 ranch dressing packets, and mix to combine. Place 1/2 cup mayonnaise in a second wide, shallow bowl.

Step 5

Bread the chicken. Coat an oven-safe wire rack with cooking spray and fit it onto the reserved baking sheet. Using your hands and working with 1 piece of chicken at a time, dip in the mayonnaise so it evenly coats the chicken on all sides, then dredge in the breadcrumb mixture, gently pressing the breadcrumbs into the chicken so they stick. Place on the rack and repeat with the remaining chicken breasts.

Step 6

Bake the chicken. Bake until the breading is golden-brown and the chicken is cooked through and registers 165°F on an instant-read thermometer, 30 to 32 minutes.