Combine raisins and bourbon. Cover with Original Chai concentrate. Allow raisins to plump, about 25 minutes. Drain, reserving liquid.
Combine 1-cup Original Chai concentrate with reserved liquid. Cook over high heat until reduced by half. Reduce to a simmer. Blend cornstarch with enough Original Chai concentrate to form slurry. Slowly add to reduced mixture. Bring to a boil. Add raisins and simmer, whisking constantly until desired consistency.