Chicken Lasagne

0ml / 2 tbsp olive oil
900g / 2lb minced raw chicken
225g / 80z / 1 1/2 cups rind-less streaky bacon rashers, chopped
2 garlic cloves, crushed
450g / 1 lb leeks, sliced
225g / 80z /  1 1/4 cups carrots, diced
30ml / 2 tbsps tomato puree
475ml / 16fl oz / 2 cups chicken stock
12 sheets (no need to pre-cook) lasagne verde

Cheese Sauce
50g / 20z / 4 tbsp butter
50g / 20z / 1 fz cup plain flour
600ml / 1 pint / 2 1/2 cups milk
115g / 4oz / 1 cup grated mature Cheddar cheese
1.5ml / 1/4 tsp dry English mustard
salt and black pepper

Heat the oil in a large flame proof casserole dish and brown the minced chicken and bacon briskly, separating the pieces with a wooden spoon. Add the crushed garlic cloves, sliced leeks and diced carrots and cook for about 5 minutes until softened. Add the tomato puree, stock and seasoning. Bring to the boil, cover and simmer for 30 minutes.

To make the sauce, melt the butter in a saucepan, add the flour and gradually blend in the milk, stirring until smooth. Bring to the boil, stirring all the time until thickened and simmer for several minutes. Add half the grated cheese and the mustard and season to taste.

Preheat the oven to 190ºC / 375ºF / Gas 5. Layer the chicken mixture, lasagne and half the cheese sauce in a 2.5 litre / 5 pint oven proof dish, starting and finishing with a layer of chicken. Pour the remaining half of the cheese sauce over the top to cover, sprinkle over the remaining cheese and bake in the preheated oven for 1 hour, or until bubbling and lightly browned on top.