This is as taught to me by my mother, but with a couple of tweaks.
1 pack of minced beef
3-4 rashers smoked bacon
1 large onion
Good squeeze of garlic, or 3-4 cloves
Double handful of mushrooms
1-2 courgettes (optional)
green pepper (optional)
1 pack of passata or chopped tomatoes
beef oxo cube
Italian herb seasoning, or a mixture of basil, parsley and oregano
black olives, if liked
Start the dish by putting the bacon into the pan and letting it crisp up, and the fat render. When that's done, add the minced beef and break it up as it cooks, adding the oxo cube, a generous shake of nutmeg, a little squirt of garlic paste, and some black pepper. Really let this brown and get all gooey; keep breaking it up with the spoon as it cooks down.
When you're happy it's browned nicely and all the juices are running, finely chop and add your onion, then put the lid on and turn everything down so that the onion has chance to cook down and soften with the meat.
While that's doing, chop the veg up; rough dice for the courgettes and peppers, and just halve or quarter the mushrooms. Add these to the pot and season well with black pepper. Give everything another ten or so minutes with the lid on to soften and saute. When that time's up, stir in your passata and tomato puree - along with the dried italian herbs, if you're using them (if you're using fresh don't add them until everything is cooked, and just stir them through at the end), and any olives. Put the lid on, reduce it to the lowest heat, and go about your business. It'll be cooked in about twenty minutes, but it'll keep getting better the longer you leave it for. If you cook it for an hour and then leave it overnight it will be stunning the next day :)
Otherwise, cook your pasta as usual, stir it into the sauce, add parmesan if you like, and scoff.
EDIT (13 April 2010):
A pork stock cube (instead of beef, Knorr make them) and a couple of leftover sausages made this quite amazing when we tried it.