Cook the macaroni pasta according to packet instructions, then drain.
Meanwhile heat the oil in a large pan then add the onion or leek, squash cubes and garlic. Cook for 10 minutes to soften slightly.
Add the stock, bring to the boil and simmer for 10 minutes, then set aside for 5 minutes and stir in the Creamy Sheese to melt. Place in a heat-proof blender and whizz up until smooth.
Return the sauce to the pan with the herbs, black pepper and salt to taste and heat up. Mix together the cornflour with a little water then whisk in as the sauce is heating up and allow to thicken. Stir in the cooked and drained macaroni.
Preheat the oven to 180 degrees C. Tip the macaroni and cheese sauce into a ceramic/glass dish then arrange the tomatoes on top and scatter over the breadcrumbs and grated Sheese.
Bake for 15-20 minutes until golden and bubbling. Now dish out between four plates and enjoy piping hot!