Cook pasta according to box instructions, generally just to al dente.
Preheat oven to 350 degrees
If using, fry pancetta in small frying pan over medium heat until browned
Grease 13x9 inch casserole dish with butter or spray
Mix all ingredients except for paprika in large bowl
Pour contents from large bowl into casserole dish
Bake for 45 minutes covered with aluminum foil.
Remove foil, and cook for an additional 15 minutes uncovered, until all the milk/liquid has been cooked into the mac & cheese.
Optionally, spread breadcrumbs along surface, which will crisp up as it finished baking.
Sprinkle paprika as desired
Bake for an additional 15 minutes uncovered, until all the milk/liquid has been cooked into the mac & cheese.