Preheat oven to 180C
Place all the vegetables in a large bowl with the oil, a pinch of salt, a good grinding of pepper and the dried herbs. Toss to coat the vegetables with the herby oil.
Pour the vegetables into a single layer on a baking sheet and roast in the hot oven for 20 – 30 minutes until browning and the carrots and parsnips are beginning to soften when you poke them with a fork.
Bring a pan of water to the boil, add a pinch of salt and the pasta and cook for 2 minutes less than the packet instructions, drain throughly and run under cold water.
Meanwhile heat the butter gently in a small pan
Add the flour when the butter has melted and cook gently for two minutes
Gradually add the milk, whisking or stirring all the time to avoid lumps
Bring to a boil, stirring while it thickens, reduce heat and simmer for a couple of minutes, still stirring.
Add two thirds of the cheese and stir until melted.
Put the pasta and vegetables into an oven proof dish and mix together.
Pour the sauce over the bake and stir.
Top with the remaining cheese, a grind of black pepper and return to the oven for 20 – 25 minutes until the cheese is browning and bubbling.