Cook macaroni noodles as directed on the package, stirring frequently. Be sure to generously salt your water. Drain and set aside.
In a dutch oven or deep dish cast iron skillet, melt butter over medium heat. Whisk in flour; continually stir and cook for 1 min to cook out the flour taste. Gradually stir in milk and crushed chicken bullion cubes and bring to boil; cook and stir until thick. Congrats, you have made a roux! Now, let's make it cheesy...
Add American (or Velveeta) and cheddar cheese; stir and cook until thoroughly melted. Remove from heat and fold in cooked macaroni then sour cream. Add salt to taste.
Sprinkle the top with breadcrumbs. Bake at 250˚for 15-20 minutes, uncovered or until breadcrumbs are light golden brown.
Serve topped with barbecue sauce for an amazing flavor kick! (optional)