1. Heat up a large saucepan of salted water and cook the pasta according to the packet instructions. Drain and leave to one side. Heat your oven to 200C/Gas Mark 6.
2. Heat the oil in a large frying pan and fry the mushrooms with some salt and pepper for 2 minutes. Add the garlic and cook for a further couple of minutes. Remove from the pan and put to one side.
3. In the same pan, fry the chicken with some seasoning and the tarragon leaves until browned (add more oil if required). Put to one side with the mushrooms.
4. Melt the butter in the frying and once it is bubbling, add the flour and whisk together. Gradually pour in the milk whilst stirring. Bring to the boil and wait for it to thicken. Continue until you have used all the milk and you have a thick white sauce. Remove from the heat.
5. Stir through the mustard, some salt and pepper and most of the mozzarella. Add the chicken, mushrooms and pasta to the sauce and combine. Put in a baking dish and top with the remaining cheese. Bake for 20-25 minutes or until the cheese is bubbling and starting to brown.
Spruce it Up
Don’t be shy with the cheese and experiment a little. You could top it with Parmesan or Fontina, if you can get hold of it, for a slightly different taste. And as always, try different shapes of pasta and use whatever you’ve got in the cupboard.