Start by preheating your oven to 350 degrees Fahrenheit. Grease your 9x13 baking dish with butter or cooking spray. This ensures the cheese does not stick to the sides while baking. A well-greased pan makes cleanup much easier later on.

Cook the elbow macaroni in salted boiling water. Drain the pasta when it is slightly firm to the bite. Do not overcook it until it is mushy. The pasta will finish softening inside the oven with the sauce.

In a large bowl, mix the beaten eggs and sour cream. Add the melted butter and salt to the mixture. Whisk everything until the base is smooth and well combined. This mixture creates the signature creamy texture.

Stir the whole milk into the egg mixture slowly. Add most of the grated cheddar cheese into the bowl. Save a small handful of cheese to sprinkle on top at the end. This creates a beautiful crust.

Fold the cooked macaroni into the creamy cheese sauce. Make sure every piece of pasta is coated well. The sauce should look thick and very yellow from the cheese. It will smell amazing already.

Pour the mixture into your prepared baking dish. Spread it out evenly with a spoon or spatula. Sprinkle the remaining cheese over the top. Bake for 30 to 40 minutes until bubbly.

Remove the casserole when the top is golden brown. Let it sit for five minutes before serving. This helps the sauce set so it is not too runny when you scoop it out.