Step 1

Preheat the oven to 350 degrees Fahrenheit and lightly spray or grease a 9x13-inch casserole dish or large oven-safe skillet.

Step 2

Stir the shredded cheese, sour cream, cream of chicken soup, 1/2 of the melted butter, diced onion, garlic salt, onion powder, and black pepper in a large bowl.

Step 3

Gently stir in the thawed and drained potatoes until combined, taking care not to over-mix. Spread the potato mixture evenly in the prepared pan and set aside.

Step 4

Carefully stir the remaining melted butter with the cornflakes, then sprinkle evenly over the top of the potatoes.

Step 5

Bake uncovered for 50-60 minutes, turning the pan around halfway through. The potatoes should be bubbling around the sides, and the cornflakes should be golden brown (if the cornflakes start to burn, tent the casserole dish with foil until the casserole is fully cooked).

Step 6

Let it rest for 10 minutes before digging in and serving with freshly chopped parsley if desired.