Onion Custard

Pare and boil twelve large onions; mash when cooked soft, and strain through a sieve; stir in, while hot, 1-4th of a lb of butter; beat half a lb sugar with the yelks of six eggs; stir into the sugar three tablespoons flour, one pint rich cream; stir all together until smooth; one tablespoon cinnamon, half spoon cloves; stir well; beat the whites of the eggs, and stir it in last; paste your pans with rich pastry; bake in a quick oven.