Bring a large pot of salted water to the boil and cook the macaroni as per the packet instructions.
Drain well and set aside.
Heat a non-stick frying pan, add the chopped bacon bits to the hot pan and fry until crispy.
Pour off any excess oil and then add the canned tomatoes.
Simmer for a few minutes to heat through.
In a medium saucepan, melt the butter.
Add the mustard.
Add the flour and stir to mix with a wooden spoon.
Using a whisk, whisk in the hot milk and continue whisking until the sauce is smooth and thick.
Cook over low heat for a few minutes to cook out the flour.
Remove from the heat and whisk in the 2 cheeses.
Once the cheese is melted and the sauce is smooth, season to taste with salt, pepper and nutmeg.
Spoon the macaroni into a baking dish and pour over the cheese sauce.
Mix the breadcrumbs and the parmesan cheese together and sprinkle this mixture over the top of the pasta.
Bake in a preheated oven at 180˚C for 20 minutes until heated through.