Before some of you start casting votes to have me hauled off to the funny farm in a fancy white jacket where the sleeves tie in back:
I actually found recipes in 3 old (pre-1930) Southern cookbooks for making homemade vanilla extract that called for using bourbon. As far-fetched as this sounds (I thought it odd, too, at first) if you read Harold McGee's book
On Food and Cooking ... it appears that our Southern ancestors were on to something since bourbon actually develops some vanilla flavors during aging that both reinforce and enhance the vanilla flavors. Remember, the flavor of natural vanilla is a combination of something like 200+ different flavors - which is why imitation vanilla can't match the flavor (depth) of the real thing since they only imitate the primary predominant vanillan flavor.
For those who don't understand what
Everclear is - it's basically unaged corn liquor which is distilled to get the highest octane possible. In the South - this would have been known in olden days as "corn liquor", "moonshine", or "white lightening". Unlike vodka it does have a more neutral flavor because it is distilled to a much purer degree of alcohol (95% vs 50% for Vodka) so it has less flavors from residual "impurities".
The dichotomy is that the higher the alcohol content of the "extraction" liquid the greater the extraction %/rate - and the higher the alcohol % of the extraction liquid the greater the flavor loss during baking! The vanilla that professional bakers use, from what I have been able to find, is 8.5% alcohol and fortified with artificial vanillan flavoring, or they use "powdered" flavorings.
I'll admit that I might be crazy - but I'm not certifiably insane, yet!