Answer:
The classic French pear brandy is the Williams Pear Brandy, which contains -- you guessed it! -- a Williams Pear. The pear isn't put into the bottle; it grows inside it. When the fruit is small, the bottle is affixed to the tree branch, and the pear grows to maturity inside the bottle. Brandy made from Williams Pears is added, and voila! The magic is complete.
Having once purchased a bottle out of curiosity (and having enjoyed the brandy immensely), I sought out the answer to this very question. And yes, if you live in a climate that is conducive to growing pears -- and a former neighbor of mine in Lake Arrowhead, CA, is a candidate for doing this, since she grows terricif pears! -- please do try it!