Instructions: Shallow oven proof baking dish with a base measurement 20 x 15cm and 5cm deep lightly buttered.

Preheat the oven to gas mark 6/400F/200C.

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

Fill a large saucepan with 2.25 litres of water containing a dessertspoon of salt and put it on the heat to bring it up to the boil.

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.

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.

Switch to a balloon whisk and keep whisking so you have a smooth sauce.

Add some salt and freshly milled black pepper as well as the nutmeg and leave the sauce to cook gently for 5 minutes.

Turn off the heat and whisk in the mascarpone and egg yolks followed by the gruyere and half the parmesan.

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 to 6 minutes until al dente (its going to get a second cooking in the oven).

When it has about 1 minutes cooking time left whisk the egg whites to soft peaks.

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.

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.

Note: To make this for four people just double the ingredients and use a 25.5 x 20 x 5cm dish increasing the cooking time by 3 to 5 minutes.

Ive made many a macaroni cheese in my time but this I promise you is the best ever.

Serves 2

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