Preheat the oven to 220C / 200C Fan / Gas Mark 7.

Cook the macaroni until it’s a bit less done than normal – a couple of minutes less than you would usually do. The brand I use takes 10 minutes normally, so I give it 8 minutes for macaroni cheese.

While the macaroni is cooking, make the cheese sauce. Melt the butter in a medium sized pan on a low heat. When the butter is foaming, add the flour and stir until it’s mixed in. Then keep cooking for 2 minutes, stirring frequently. It takes guts to do this. It looks like something is going to go wrong but it doesn’t!

Very gradually add the milk, stirring constantly. Make sure each bit of milk is incorporated before adding the next bit. If you do this slowly on a very low heat, you should end up with a perfectly smooth cheese sauce with no lumps and no need to whisk. However, if it does go wrong for some reason, you can always use a whisk to beat out the lumps.

When all the milk is incorporated, add the mustard, salt and pepper. (N.B. I use salted butter, so I don’t add any extra salt here.) Then add half the cheese, stir to combine and turn off.

When the pasta is done, drain it, retaining a little bit of the cooking water.

Tip the pasta and a couple of tablespoonfuls of the cooking water into the cheese sauce and stir.

Add the cooked turkey to the macaroni cheese and stir again.

Pour the macaroni cheese into a shallow ovenproof dish and sprinkle over the remaining cheese.

Bake in the oven for 10 minutes. The top should be brown, but the bottom should still be saucy and the macaroni should be perfectly cooked.