Carnie Wilson's Fall to Your Knees Mac and Cheese from "To Serve With Love"

Why I Love This Recipe
Diane Sawyer's favorite Macaroni and cheese recipe, shared during GMA's Mac 'n' Cheese challenge (2008).
Ingredients You'll Need
3½ cups large elbow macaroni
10 ounces Velveeta cheese, cut into 1-inch squares
10 ounces. white Vermont cheddar cheese, cut into 1-inch squares
15 ounces Gruyère cheese, shredded
1-2 cups of jack and cheddar cheese (combined), shredded
4 ounces cream cheese (at room temp.)
2/3 cup sour cream
1 1/3 cups heavy cream
1 1/3 cups half-and-half
1 egg
2 2/3 tablespoon flour
1 tablespoon. Worcestershire sauce
1 teaspoon garlic powder
1 teaspoon onion powder
1 teaspoon dry mustard powder
1/8-1/4 teaspoon. cayenne pepper
1/8 teaspoon nutmeg (fresh if you have it)
1 teaspoon. kosher salt
A pinch of paprika
1 tablespoon fresh chives (for garnish)
Directions
1. Grease a 9-inch-by-13 inch nonstick metal baking pan with 1 tablespoon butter. Preheat oven to 350 degrees F. Prepare macaroni according to the package directions, but make sure it's al dente. (Huh? It should still be a little firm.) Be sure to add a pinch of salt and a dash of olive oil to the boiling water while cooking. Drain pasta well and pour into the baking pan.
2. In a large mixing bowl, add the heavy cream, half-and-half and sour cream; break the cream cheese into little bits with your (clean!) fingers as you add it to the bowl. Add the egg, flour, Worcestershire sauce, garlic and onion powders, dry mustard, cayenne pepper and nutmeg; combine very well with a wire whisk to break up that cream cheese. It will look lumpy, but that's OK.
3. Starting at the corners of the pasta dish, place and push down the Velveeta and white Vermont cheddar cubes. Work your way around and toward the middle (they won't push down completely, but just smoosh them down a bit). Now sprinkle the fabulous Gruyère cheese evenly over the top -- gently and evenly pour that artery-clogging mixture on it, covering all areas. Gently shake the pan afterward for a sec to make sure the liquid is even. I know it sounds gross, but push down and make little holes into areas of the mixture with your fingers. (You're just getting some of that Gruyère down deeper below the surface.) Wash your hands!
4. Sprinkle the jack-and-cheddar combo over the mixture and sprinkle the paprika on top. Put this baby in the oven (make sure your oven rack is right in the middle) and bake until brown and bubbly — we're talking approximately 30 minutes. It will be creamy in the center and more crusty on the top and edges. Chop some fresh chives and get those taste buds ready. When it's done, garnish with the chives (but try not to eat part of the crusty top before you serve it. I'm watching you!).