Preheat the oven to 375°F.

Combine the flour, garlic salt, and white pepper in a shallow bowl.

Whisk together the egg, buttermilk, sour cream, and melted butter in a separate shallow bowl until smooth.

Combine the cheddar cheese, crushed cornflakes, Parmesan, and parsley in a third shallow bowl.

Line a rimmed baking sheet with foil and place a wire rack inside baking sheet.

Pat the chicken dry and sprinkle with the salt and pepper. Working in an assembly line, coat a chicken breast in the flour mixture and shake off excess. Next, dip chicken in egg mixture and let excess drip away. Finally, dredge chicken in the cornflake mixture and transfer to the prepared baking sheet. Repeat with the remaining chicken.

Bake the chicken on middle rack of oven until crust is crisp and golden and chicken has reached an internal temperature of 165°F, 35-40 minutes.

Check to see that chicken is done. Remove from oven or add time as needed.

Transfer the chicken to a plate and serve immediately.