Assuming you've purchased the first eight bottles we've recommended, you've got yourself a pretty good starting point for a home bar. We've introduced three base spirits and five modifying bottles. We haven't added a base since bottle three, but that's precisely what we're doing here. For your ninth bottle, we suggest brandy.
Brandy is a french spirit that is made, rather simply, by distilling wine. The name comes from the dutch brandewijn, which translates loosely to "burnt wine." Some brandies (typically higher quality ones) are aged in oak casks for a time. There are many varieties of brandy, but we recommend purchasing a Cognac brandy. Cognac is a variety of brandy produced in a specific region in France. Basically, Cognac is to brandy what Champagne is to sparkling wine. Cognac has a grading system that denotes the age of the product. V.S. Cognacs have been aged for at least two years in a cask, and typically represent a good intersection of price and quality for making cocktails.
Adding another base at this stage in the game opens up a lot of opportunities for new cocktails to try; we're going to post a bit more frequently the next two weeks with some of our favourite brandy cocktails.