After experimenting many times to make my own Vanilla Extract, this is the recipe I settled on quite a few years back... it's simple and makes a large bottle full, which after letting age, I decant a bit into a smaller bottle...
Simple Vanilla Extract
Take a bottle of Dr. McGillicuddy's Raw Vanilla Schnapps
Pour it into a pot on the stove over medium-low heat.
Slit two or three Vanilla Beans lengthwise, scrape out the insides and add this to the simmering Schnapps.
Cut the slit and scraped beans into 1" pieces and add these to the pot as well.
Allow the mixture to simmer gently for about 10 minutes, then remove from heat. Let cool completely, then bottle and let sit in a cool, dark cupboard to age for at least a month. (I pour it all, including the vanilla bean pieces, back into the Dr. McGillicuddy's bottle) After this point, you can decant into smaller bottles, if desired, and include a piece or two of the vanilla bean in each smaller bottle. I remove only a small bottle's worth to use in my baking, and keep the large bottle in the back of the cupboard to continue working. When the larger bottle gets down to the end, I strain off the pieces of vanilla bean from the first bottle and use them to start a second batch. (You can add a fresh vanilla bean along with these pieces) Just continue this process to make other batches.