Step 1

Preheat the oven to 350 degrees F.

Step 2

Grease a 3-quart baking dish.

Step 3

Cook the spaghetti until al dente according to the package directions.

Step 4

Drain the pasta.

Step 5

In a large bowl, combine the cream of chicken soup, cream of mushroom soup, sour cream, milk, 2 tablespoons butter, parsley, garlic powder, salt, and pepper.

Step 6

Add the mozzarella cheese, parmesan cheese, celery, onion, and mushrooms.

Step 7

Stir in the chicken and the pasta.

Step 8

Transfer the mixture to the prepared baking dish.

Step 9

Combine the cornflakes and the remaining butter.

Step 10

Sprinkle the cornflake mixture over the top of the mixture.

Step 11

Bake, uncovered, until bubbly, about 45-50 minutes.

Step 12

Serve hot.