Preheat the oven to 190°C, fan 170°C, gas 5.
Put the bacon rashers and halved tomatoes onto a baking tray, drizzle with the oil and roast for 20 mins or until the bacon is slightly crisp and the tomatoes soft.
Make a quick all-in-one sauce; put the butter, flour and milk into a pan and heat gently over a low heat, stirring all the time. You may need to swap the spoon for a whisk as the sauce begins to thicken. Gently simmer for 5 mins. Add the mustard.
Add most of the two cheeses (keep some back for the top) to the sauce and a little freshly ground black pepper and stir well.
Bring a large pan of water to the boil and cook the macaroni according to the pack instructions. Drain well and tip it back into the empty saucepan.
Spoon or pour half of the cheese sauce over the pasta and mix together. Rub a little butter over 4 ovenproof dishes. Chop the bacon and add to the adult or toddler dishes. Add the tomatoes to all of the dishes.
Spoon the rest of the sauce over the top and sprinkle over the remaining cheese. Cook in the oven for 20 mins or until it is golden brown and bubbling. Serve with the vegetables.