You can use the insides of a pumpkin that has been hollowed out for Halloween, but you need chunks, not slices.
I keep it in instant coffee jars because they have plastic screw-top lids. (The vinegar will soon corrode metal.)
500 - 600 g (1 ¼ lb) piece of pumpkin (includes skin - say 450 g of the good bits)
Peel the pumpkin and discard the soft centre. Cut it into small cubes (about 2 cm - ¾ inch).
Pour boiling water over the tomatoes, and skin and slice them.
Peel and slice the onions and garlic.
Lightly crush the pepper corns and allspice berries.
Put all the dry ingredients into a large pan, stir and add the vinegar.
Bring to the boil gently, then cook steadily until the mixture is jammy and has just a little free liquid. This will take about an hour.
When cool pour into the jars, cover with a ring of greaseproof paper and the lid. Store in the dark.
I usually distrust and dislike chutney. It seems like a case of garbage in, garbage out. If you use first class ingredients the result can be great - as this Pumpkin Chutney shows. It is adapted from a recipe in Elizabeth David's "Spices, Salt and Aromatics in the English Kitchen".
Ingredients for 2 jars:
500 g (just over 1 lb) ripe tomatoes
125 g (4 oz) onions
50 g (2 oz) sultanas
350 g (¾ lb) soft brown sugar
15 ml (tablespoon) salt
5 ml (teaspoon) each of ground ginger, black pepper corns and allspice berries
large clove of garlic
375 ml (13 fluid oz) wine vinegar