Remove the bacon rind and snip the bacon into small pieces. Fry the bacon until slightly crisp. You may need a little fat or oil for this you may not. Put the bacon in a dish to cool and fry the onion, after chopping it up, in the same pan. Do not be too fierce with the heat, the onion should not be crisp, but soft and flavoured with the bacon fat. Put the onion aside to cool too. The chestnuts should ideally be roasted on an open fire. I have the luxury of a chestnut pan and a coal fire so that is how I do them. You can par boil the nuts or even part cook them in a microwave if you have no fire.
However you cook the chestnuts you need to puncture the skin of the nut. The best way to do this is to cut a cross in the base of the chestnut. I first saw Michael Barry do this on television a number of years ago. If you are going to microwave the nuts you probably want to remove the outer skin before cooking. Roasted nuts are very easy to peel, boiled or microwaved ones are slight more fiddly. The chestnuts should be roughly chopped, I like quite large lumps so I quarter mine. I would go no smaller than quarter of an inch pieces. Please do not puree the chestnuts. Bread crumbs can be made in a food processor or between fingers and thumbs. Once you have the ingredients at this stage, find your self an large bowel and mix all but the egg together. Once everything is fairly well mixed add the egg to bind the mixture together. You can use a wooden spoon, or better your hands, for mixing.
Pack the mixture into a tin for roasting, or your turkey if you want. I tend to like the stuffing cooked separately and as this is a pretty meaty mixture it can make a meal on its own. Cook the stuffing in an oven at about 180 C for 45 to 55 minutes. Vary the time and temperature depending on the tin you are using. A deeper tin, like the loaf tin, will probably need a longer time at a slightly lower temperature.
The stuffing is delicious hot with a roast and also excellent cold, especially as a sandwich filling. It has done a pretty good job of converting even people who do not like nuts to chestnuts. Unfortunately chestnuts are only available in the UK during the run up to Christmas and just after. If you cook the chestnuts you can freeze them if you want to enjoy this recipe at some other time of the year.