In large saucepan, combine first four ingredients; stir in milk. Add butter; stirring constantly, bring to a boil over medium-high heat and boil 1 minutes. *This is very important but make sure you don't burn the milk or else you will get an undesirable smoky taste to your dish!* Remove from heat.
Stir in 4 coups cheese until melted. Add elbows. Pour into lightly greased 9x13 casserole.
Coarsely shred bread in food processor, then mix crumbs with the remaining cup of cheese. Spread over top of macaroni.
Bake uncovered in 375 degree oven for 25-40 minutes until browned to desired doneness.
Enjoy! Makes great leftovers!
*Cheese should be 3 Cups Reduced Fat Sharp Cheddar and 2 Cups Reduced Fat Mexican Four Cheese Blend.