In a food processor, whirl yogurt and 1/4 cup cashews until nuts are finely ground.
Sprinkle chicken with 1 tsp. salt.
Pour olive oil into a large, deep frying pan over medium-high heat. When hot, add chicken and cook, stirring occasionally, until lightly browned all over, about 8 minutes. With a slotted spoon, transfer to a bowl.
Add onion to pan; cook, stirring occasionally, until lightly browned, 5 minutes. Reduce heat to medium; add tomatoes, garlic, ginger, cardamom, cinnamon, coriander, garam masala, and cayenne. Cook until tomatoes begin to soften, 2 minutes.
Return chicken and juices to pan, along with raisins, remaining 1/2 cup cashews, and yogurt mixture. Reduce heat to medium-low, cover, and cook, stirring often, until chicken is no longer pink in the center (cut to test) and sauce has thickened slightly (it will look separated), 10 to 15 minutes. Uncover, add cream, and stir over medium heat until sauce is smooth and hot, 5 minutes.
Add more salt to taste.
Wine note: Typically full of honeyed tangerine, peach, and honeysuckle, Viognier--the great white grown in France's Rhne Valley--is rich but, at its best, crisp and minerally too. It pairs well with creamy sauces and aromatic spices. Leaner versions stand up to spicy Thai and Vietnamese flavors; richer ones are good matches for nuts, cheese, mild Indian curries, and sweet shellfish.
Miner Family Simpson Vineyard Viognier 2005 (California; $20). A rich mouth-feel and hint of tangerine peel set off the chicken korma.
Voss Viognier 2004 (Carneros; $26). Delicate tangerine peel, peach, and honeysuckle, with minerals that keep step with the chicken korma.
