Souffled Macaroni Cheese

Begin by having all your ingredients weighed out and the cheeses grated.

Fill a large saucepan with 4 pints (2.25 litres) of water containing a level dessertspoon of salt and put it on the heat to bring it up to the boil. Then, in a small saucepan, melt the butter over a gentle heat, add the onions and let them soften, without browning and uncovered, for 5 minutes.

Then add the flour to the pan, stir it in to make a smooth paste, then gradually add the milk, a little at a time, stirring vigorously with a wooden spoon. Then switch to a balloon whisk and keep whisking so you have a smooth sauce. Then add some salt and freshly milled black pepper, as well as the nutmeg, and leave the sauce to cook gently for 5 minutes. After that, turn off the heat and whisk in the mascarpone and egg yolks, followed by the Gruyère and half the Parmesan.

Next place the baking dish in the oven to heat through, then drop the macaroni into the boiling water and, as soon as the water returns to a simmer, give it 4-6 minutes, until al dente (it's going to get a second cooking in the oven).

When it has about 1 minute's cooking time left, whisk the egg whites to soft peaks, you can watch how to do this in our Cookery School Video on this page. Drain the pasta in a colander, give it a quick shake to get rid of the water, then tip it back into the pan and stir in the cheese sauce, turning the pasta over in it so it is evenly coated. Then lightly fold in the egg whites, using a cutting and folding movement so as to retain as much air as possible. Remove the warm dish from the oven, pour the pasta mixture into it, give it a gentle shake to even the top, then scatter the reserved Parmesan over and return the dish to the oven on a high shelf for 12 minutes or until the top is puffy and lightly browned.

Serve it, as they say in Italy, presto pronto.