Grease or spray two 9x13” glass baking dishes.
Set aside.
Fry bacon until crisp.
Drain, set aside on paper towels to drain.
When bacon is cool, crumble into bite sized pieces.
Set aside.
Meanwhile, bring a very large 16-qt. stock pot filled about 2/3 full of water to a boil.
Add macaroni and cook according to package directions, except al dente.
Rinse with cold water and drain.
In a large Dutch oven, melt butter over low to medium heat.
Add green onions and saute until tender – a couple of minutes.
Add flour and whisk to combine.
Add milk about ¼ cup at a time until all the milk is incorporated.
Add half-and-half the same way.
Season with salt, pepper, parsley and hot sauce.
Add cheese and continue stirring until cheese is melted.
Combine with macaroni and pour into prepared baking dishes.
Sprinkle the tops with the bacon.
Bake at 350 degrees about 15-30 minutes, or until hot and bubbly. (See note below).
Serve immediately.