Cook pasta in large pot of salted water to al dente. Drain pasta and leave to cool.
To begin the roux, melt butter in seperate medium pot. Whisk in flour and mustard, stirring while cooking for about 5 minutes. Stir in the milk and continue cooking and stirring until liquid begins to thicken. Then stir in onion, bay leaf, paprika, cayenne pepper, chili powder, cumin and hot sauce. Let simmer for ten minutes, stirring frequently. Remove the bay leaf.
In small bowl, whisk egg until smooth and temper into the roux. Stir in 3/4 of the cheese. Stir until cheese is melted and egg is mixed throughout. Season cheese sauce with salt and pepper.
Pour half the cooked macaroni into 2 quart casserole dish. Pour half the cheese sauce over the macaroni. Pour remainder of macaroni in casserole dish and top with remaining cheese sauce. Mix well and sprinke leftover cheese on top.
*If a topping is desired, melt 2-3 TBSP Smart Balance and mix with 3/4 cup whole wheat or Panko bread crumbs. Sprinkle over top of macaroni.*.
Bake at 350 for 30 minutes. Remove from over and let sit for 5 to 10 minutes before serving.