Crisp-topped mac ’n’ cheese with tomatoes & green beans

Preheat the oven to 200ºC, gas mark 6. Put the milk in a saucepan with the onion or leek top, bay leaf and peppercorns. Bring to just below boiling then set aside for 15 minutes to infuse. Strain the milk into a jug

Melt the butter in a medium-sized saucepan over a medium heat. Add the flour, stir to create a paste and cook for 3 minutes, stirring occasionally. Take off the heat and beat the milk into the pan in 4 additions, beating after each one until smooth. Return to the heat and simmer for 1-2 minutes, stirring often, until thickened. Take off the heat and add 150g Cheddar and the mustard. Season to make a well-flavoured sauce, then set aside.

Cook the macaroni according to pack instructions, until almost done. Meanwhile, heat the oil in a frying pan and add the tomatoes. Season and cook over a high heat for about 5 minutes, until starting to caramelise. Drain the pasta, combine it with the cheese sauce, then gently fold in the tomatoes and their juices.

Transfer to a large oven dish. Roughly crush the crisps in the bag, then open and combine with the remaining 25g cheese. Scatter over the pasta. Bake for 20-25 minutes, until bubbling and golden on top. Cook the green beans according to pack instructions and serve alongside.