Directions
1.    In a large bowl, toss together pasta with the cheese cubes and pour into a greased 2qt oven safe baking dish.
2.    In a large bowl mix together the flour, salt, black pepper, cayenne pepper, dry mustard, nutmeg and sour cream, egg, heavy cream and half-and-half.
3.    Pour the mixture over the pasta and cover with shredded Cheddar.
4.    Bake uncovered at 350 degrees until top is just beginning to brown, about 35 minutes.
5.    Cut the bread into crouton-sized squares. In a skillet over medium heat, melt butter, add cubes and toast until golden. Sprinkle the bread cubes on top of the macaroni and cheese and bake until golden brown, about 10 minutes more.
6.    *Note: to make this even easier I just sprinkle dried breadcrumbs on top of the casserole and then spray it with pam and bake it for ten more minutes — that trick right there will save you another 5-10 minutes .