Method

​1 Preheat the oven to 200°C/fan 180°C/gas mark 6. Heat the oil in a frying pan, and gently cook the leeks for 6-8 minutes until soft; remove and set aside.

2 Fry the chopped bacon until crispy, then set aside. Cook the pasta for 5 minutes, drain, and then return to the pan. You can start making the sauce once your pasta is cooking.

3 Melt the butter in a saucepan, stir in the gluten-free flour and cook for 1-2 minutes. Over a very low heat, gradually stir in the milk. Cook for 5-6 minutes, stirring continuously, until smooth and thickened. Stir in the mustard and half the cheese, then season to taste.

4 Add the leeks and bacon to the pasta, stir well, pour over the sauce, then toss together to coat. Transfer to an ovenproof baking dish.

5 Mix together the breadcrumbs and remaining cheese, season with black pepper and scatter over the top of the pasta. Bake for 20 minutes until golden and bubbling around the edges.