Pleasy don't pester me with silly questions like "how many prunes?". If you really can't decide such a simple thing for yourself, grab a Ouija board and ask Mme. Greenbaum.
Lay the prunes in white wine for two days; then put on a wire sieve to drip, but do not squeeze them. When they look dry, which will be in about half an hour, lay in glass jars with alternate layers of sugar and stick cinnamon and a few pieces of mace and a very few cloves. When the jars are full, fill up with cognac and seal. Set in the sunniest place you can find for three days.