Cook egg noodles according to package directions, then drain.

Chop cooked chicken into bite-sized pieces.

In a large bowl, combine cooked noodles and chopped chicken.

In a separate bowl, melt butter and mix with cream of chicken soup until blended.

Add sour cream, salt, pepper, and chopped green onions to the soup mixture and mix well.

Incorporate 1 1/2 cups of shredded cheddar cheese into the mixture.

Pour the combined mixture into a buttered 2 1/2-quart baking dish.

Bake in a preheated oven at 350 degrees Fahrenheit for 30 minutes.

In a small bowl, combine the remaining 1/2 cup of shredded cheddar cheese with crushed corn flakes.

Sprinkle the cheese and corn flake mixture over the casserole.

Continue baking for an additional 10 minutes, or until the cheese is melted and bubbly.