Arrange chicken breasts in a greased 9x13 dish, ensuring even spacing. If any pieces are thicker, gently pound them to ensure uniform cooking.

In a bowl, combine the ranch packet and sour cream, stirring until smooth. Let the mixture sit at room temperature for a few minutes to enhance the flavors.

Spread the creamy ranch mixture generously over the chicken, making sure every piece is well-coated. Top it all off with a generous layer of shredded cheddar cheese.

Place the dish in a preheated oven at 375°F. Bake for about 25 minutes or until the cheese is golden and bubbly, and the chicken reaches an internal temperature of 165°F.

After baking, remove the dish from the oven and let it rest for 5 minutes to retain the juices.