Use 100g of pasta per person/serving, so if you want to have 2 guests over, boil cca 300-400g of any type of pasta you like. Bring a large saucepan of water to the boil and add the pasta and plenty of salt - Nigella says the water should be as salty as the Mediterranean Sea. Give it a stir and cook for 10 min, whilst uncovered. When the pasta is cooked, drain quickly (keep about a cup of water to add to the sauce) and rinse with cold water.
Meanwhile, heat about 50g butter or spread in a deep frying pan (you can use 2 tablespoons of olive oil as well) and add one clove of garlic, gently cooking for 1 minute. Add a quarter of a very fine chopped onion and anything you like from the following: bacon, prawns, salami, sausages, salmon, mushrooms, all chopped. After frying for another 2 minutes on a medium heat, add around 200g of a good quality tomato sauce, your pasta water (additional sun dried tomatoes are great if you like them) and some spices (I usually use rosemary, pepper, oregano and dried parsley). Boil until the sauce is somewhat more consistent, you can add a tablespoon of white flour if it's too thin.
You can serve either simple pasta and the sauce on top or mix the pasta with the sauce, I add some double cream on top to make it even better (If you count calories, I'd leave that aside :D) And that's it! Let me know if it turned out great!
Bon Appetit!