Ultimate Macaroni and Cheese

Credit goes to the Horseradish Grill in 
Atlanta and also Bon Appetit magazine.  This 
is absolutely decadent and the best I've ever 
had.

Ultimate Macaroni and Cheese

   1 3/4  cups          small elbow macaroni
   1 1/4  cups          extra-sharp cheddar cheese (5 oz) -- cubed
   2 2/3  tablespoons   flour
   1 1/2  teaspoons     salt
   1 1/2  teaspoons     dry mustard
     1/4  teaspoon      ground pepper
     1/8  teaspoon      cayenne
     1/8  teaspoon      ground nutmeg
   1 1/3  cups          half and half
   1 1/3  cups          whipping cream
     2/3  cup           sour cream
   2      large         eggs
     3/4  teaspoon      Worcestershire sauce
   1 1/4  cups          packed extra-sharp 
cheese (5 oz) -- grated

Preheat oven to 350. Lightly butter 
9x13x2-inch glass baking dish. Cook
macaroni in lg saucepan of boiling salted 
water until just tender but
still firm to bite. Drain pasta. Transfer to 
prepared dish. Mix in cubed
cheese.

Whisk flour, salt, mustard, black pepper, 
cayenne pepper and nutmeg in
medium bowl until no lumps remain. Gradually 
whisk in half and half, then
whipping cream and sour cream. Add eggs and 
Worcestershire sauce; whisk to
blend. Pour over macaroni mixture; stir to 
blend. Sprinkle grated cheese
over.

Bake macaroni and cheese until just set 
around edges but sauce is still
liquid in center, about 25 mins. Remove from 
oven; let stand 10 mins to
thicken slightly (sauce will be creamy).