Vanilla Bourbon or Another Recommendation ?

Whenever I am out of vanilla extract (it's a rare occurrence), I use rum. Tastes like vanilla to me.

There's no need to seek out a vanilla flavored spirit as they are two discrete ingredients. That makes little sense as a pantry purchase if you aren't going to regularly use it.

Just replace the bourbon with another preferred spirit (brandy, cognac, rum, whatever) or omit it. If you omit both the bourbon and vanilla extract, you'll just end up with plain rice crispies like the recipe from the back of the cereal box.

I had a vanilla vodka and it’s still on the market. But I find flavoured vodkas heavy or artificial in their flavouring.
You could use any brandy (unsweetened), distilled (rum, tequila) or liqueur you like.