I got this recipe from Delia Smiths' "How To Cook: Book One". I feel that the title of this book is a bit misleading; it makes it sound like all the recipes in here are very simple when in reality some of them are quite difficult (although she does tell you how to boil an egg!)

I have made this meal for my family on many occasions; it is absolutely delicious, although very fattening and quite difficult to make! I would recommend it if you're a cheese lover, as it is packed full of the stuff. The recipe as it is can be quite expensive to make, as the Gruyere cheese isn't cheap. If I'm doing this as more of a "budget" meal I replace the Gruyere and the Parmesan with an equal amount of Cheddar; this doesn't give the dish such an interesting flavour but it's definitely cheaper and still very tasty!

This dish is lovely served with a green salad or some garden peas, and the obligatory "garlic wi' bread".

Ingredients:
175 macaroni
25 g butter
1 medium onion, peeled and diced
25g plain flour
275ml milk
1/4 whole nutmeg, freshly grated (I personally just use nutmeg out of the spice rack; a couple of generous pinches should do)
75g Mascarpone cheese
2 large egg yolks, lightly beaten
2 large egg whites
50g Gruyere, finely grated
50f Parmesan, finely grated (I use the ready prepared stuff from Tesco!)
salt and black pepper to season

Method:
1) Weigh all ingredients out and grate the cheese. Preheat the oven to gas mark 6 / 200C. You will need a shallow ovenproof baking dish with a base measurement of 20x15cm, 5cm deep, and lightly buttered.
2) Fill a large saucepan with water (add a dessertspoon of salt if you wish, I personally don't use it when cooking pasta) and bring it to the boil.
3) In a small saucepan, melt the butter over a gentle heat, add the onions and let them soften, without browning and uncovered, for about 5 minutes. Then add the flour to the pan, stirring it in to make a smooth paste, then gradually add the milk, a little at a time, stirring vigorously with a wooden spoon (Delia then says to whisk with a balloon whisk but I don't think this is necessary, just more washing up!)
4) Add the nutmeg and season, and leave the sauce to cook gently for about 5 minutes. Then turn off the heat and stir in the Mascarpone and egg yolks, followed by the Gruyere and half of the Parmesan (or Cheddar cheese if using instead).
5) Place the baking dish in the oven to heat through, then add the macaroni to the boiling water and cook untl al dente (should take about 5 minutes).
6) Whisk the egg whites to soft peaks.
7) Drain the pasta, then tip it back into the pan and stir in the cheese sauce, ensuring that the pasta is evenly coated.
8) Lightly fold in the egg whites, using a cutting and folding movement.
9) Take the warm dish from the oven and pour the pasta mixture into it; sprinkle the remaining Parmesan (or Cheddar) over the top. Return the dish to the oven and cook for approximately 12 minutes or until lightly browned and risen.
10) Serve immediately.

Delia says that this amount will serve two people generously; I personally find that it is enough to feed my hungry husband, eight year old daughter, two year old son and myself when served with a salad or some veg and bread.

This does sound like quite a "faffy" recipe but it is well worth the time it takes to prepare as it is delicious!