01 - Preheat oven to 375°F. Lightly grease a 9x13-inch baking dish with cooking spray or butter.
02 - Pat chicken breasts completely dry with paper towels. Season both sides generously with kosher salt and black pepper. Arrange seasoned chicken in a single layer in the prepared baking dish.
03 - In a medium bowl, whisk together sour cream, mayonnaise, chopped green onions, dry onion soup mix, garlic powder, onion powder, and milk until completely smooth and well combined.
04 - Spread the sour cream and onion mixture evenly over each chicken breast, covering completely.
05 - Sprinkle shredded cheddar cheese evenly over the sauced chicken. Top with crushed gluten-free crackers or potato chips for added crunch, if desired.
06 - Bake uncovered for 25 to 30 minutes, or until chicken reaches an internal temperature of 165°F and the sauce is bubbly around the edges.
07 - Let the chicken rest for 5 minutes before serving to allow juices to redistribute. Garnish with additional chopped green onions and serve hot.