Mix brown sugar, cinnamon & vanilla in large bowl with wire whisk.
Peel bacon apart into individual pieces,.
Take 12 pieces of bacon and drop them into bowl. Mix everything with your hands until all the bacon is evenly coated with the sugar mixture and there is no loose sugar in the bottom of the bowl.
Take 1 slice of apple and 1 piece of bacon. Wrap bacon around apple, secure loose end with toothpick.
Repeat until you have them all wrapped.
I like to cook them on the grill - indirect over low to medium heat until the bacon is cooked. I check them about every 30 minutes, and might turn them over once. You could accomplish the same thing in an oven - about 300 degrees, checking every 30 minutes or so until bacon is done. Usually somewhere between 50 & 70 minutes.
Watch the hot sugar, it'll burn you.
Once the bacon is done, remove & cool on rack.
They're great all by themselves, or cut up with a scoop of vanilla ice cream. I've also done them with orange zest in the sugar in place of the vanilla.