Cognac is a brandy produced in the Cognac region of France from white grapes that have been double distilled and aged in oak barrels. The production process involves harvesting grapes in late September through November, pressing them to extract juice which is fermented and distilled twice in pot stills. The resulting spirit, called "bonne chauffe", is aged for at least 3 years in Limousin or Tronçais oak barrels, during which time it loses volume to evaporation and gains color and flavor from the wood. Cognacs are blends of spirits from different barrels and regions, with "Grande Champagne" denoting spirits from the finest grape-growing area.