Finely chop the onions and garlic. (To be honest, I would do this in the processor every time. It is not just that it is easier, but that it makes the onion meld into the sauce so well later.
Heat the oil in a heavy-based pan and cook the very finely chopped onion and garlic over a low heat until you have a soft, golden mush, about 10 minutes.
Add the brown sugar (though white is fine too), stir it in and let the onion mixture cook for another minute or so.
Remove the anchovies from the tin and chop them very finely; I use my mezzaluna for this.
Add them to the onion mush, stirring until they begin to ?melt?, then stir in the butter and the pinch of ground cloves, followed by a tablespoonful of water.
When all is combined, gradually stir in the milk.
When this has come together as a puré, take the pan off the heat.
Meanwhile, cook the pasta in abundant salted water according to the packet instructions, removing a ladleful of cooking liquid just before you drain it.
Tip the drained pasta into the anchovy and onion sauce and add the reserved cooking water to help lubricate the pasta. You may not need all the water, so pour it in gradually.
Add some oil from the anchovy tin if you need it too.
And of course, if the pan is not big enough to take all the pasta, just put it back into the pan it was cooked in and pour the sauce over the top.
Sprinkle over most of the parsley, just roughly chopped, thoroughly turning the pasta in the pan to coat each strand in the anchovy sauce.
Remove to a warm bowl, sprinkle over the remaining parsley and take to the table.
NOTE: If you are cooking pasta for a dinner party or any other occasion when you might be surrounded by people and forget to take the pasta off in time, you stand much less chance of overcooking it by following the Agnesi method.
Bring your water to the boil, add salt, then tip in the pasta stirring well to make sure it?s all in and not clumped together.
Once the water has come back to the boil, let the pasta cook for two minutes, then turn off the heat, cover the pan with a thin tea towel and clamp with a tight-fitting lid. Let the pasta stand like that, for as long as the packet tells you to cook it by the normal method. Then drain it, remembering to remove the ladleful of cooking water before doing so.