In a medium saucepan saute the bacon and onion until the bacon is cooked through and the onion is transparent.
Add most of the milk to the saucepan and let slowly come to the boil. Mix the remaining milk with the cornflour. Just before the milk boils stir in the cornflour mixture and continue stirring.
Add the two cheeses to the white sauce while continuing to stir until melted. Add the cooked macaroni and stir until the sauce well coats the pasta.
Place spoonfuls of mac and cheese into ramekins then sprinkle with breadcrumbs, herb rub and paprika. Place in the oven at 180 degrees C or place under a grill until the top melts and a crust is formed.