What kind of cognac is it? If it's anything VSOP or better I wouldn't pour it over the cherries (um... unless it was mine!

: ) However, if it
were my cognac I'd definitely appreciate it, especially the eating of the cognac cherries part! I love me some cognac! Rawr!
There are inexpensive Sherrys and Brandy, just like wine, and they make fine infusions! I used the cheapest liquors for mine because they end up tasting more like whatever you infuse them with (& it's cheaper!

)
You can cover the cherries in sugar first, which I did for the Limoncello (which is traditional), but I prefered the no-sugar infusions. You could taste the complexity & it wasn't a syrup liquer, which I only like as additions to cocktails or as a flavoring. Personal choice!
I googled the cognac & found this:
http://www.fortnumandmason-usa.com/P...ac,171,14.aspx
Looks like if you start infusing them in cognac you've got yourself a business!

I also found this amazing recipe that only infuses the cherries in sherry for 24 hours!!! Um... yummmm....
http://www.oprah.com/recipe/omagazin...erry-ice-cream
I imagine you could also use the cherries in a delicious salad or, like the PP mentioned, an awesome chutney. I bet infused cherries & pickled onions (onions covered in vinegar & let to sit) or carmelized onions would be
amazing!
I recently had a sherry "martini" with dry sherry, Auchentoshan whiskey & a sherried cherry as a "garnish" which I totally ate

Sherried cherries would make a great "bar snack" too, which I bet your Uncle would love considering he's an old school cognac kind of guy.
Go out & buy some el cheapo liquor & tell us how it turns out!!!