Step 1

Cook the macaroni in a large saucepan of boiling salted water for 8–10 minutes. Drain well and set aside.

Step 2

Melt the butter over a medium heat in a saucepan slightly larger than that used for the macaroni. Add the flour and stir to form a roux, cooking for a few minutes.

Step 3

Gradually whisk in the milk, a little at a time. Cook for 10–15 minutes to a thickened and smooth sauce.

Step 4

Meanwhile, preheat the grill to hot.

Step 5

Remove the sauce from the hob, add 175g/6oz of the cheese and stir until it is well combined and melted.

Step 6

Add the macaroni to the sauce and mix well. Transfer to a deep suitably-sized ovenproof dish.

Step 7

Sprinkle over the remaining Cheddar and the Parmesan and place the dish under the hot grill. Cook until the cheese is browned and bubbling. Serve straightaway.