Begin by greasing a 9x13 inch baking dish with softened butter or cooking spray. Prepare a piece of aluminum foil for later use.

Bring a large pot of water to a rolling boil. Optionally, add a pinch of salt. Cook the egg noodles as per the package directions but remove them 1 to 2 minutes early. Before draining, set aside 3/4 cup of the pasta cooking water.

After draining the noodles, return them to the pot.

Combine the sour cream, onion soup mix, melted butter, chopped parsley, and 3/4 cup of crispy fried onions in a large bowl. Whisk until well blended.

Stir in 1/4 to 1/2 cup of the reserved pasta water gradually until the mixture reaches a slightly thinner consistency.

Pour the creamy mixture over the hot noodles and gently stir to coat them evenly. Then transfer the mixture to the prepared baking dish.

Top the casserole with 1/2 cup of crispy fried onions, reserving the last 1/4 cup. Cover the dish tightly with aluminum foil.

Place the dish in a preheated oven set to 350°F and bake for 15 minutes. Afterward, remove the foil and sprinkle on the remaining fried onions. Bake uncovered for another 5 minutes until golden brown on top.