Instructions

Process 3 tablespoons roasted cashews in blender on low speed to consistency of fine gravel mixed with sand, 10 to 15 seconds. Add ¾ cup hot water and process on low speed until combined, about 5 seconds. Scrape down sides of blender jar and let mixture sit for 15 minutes. 
Meanwhile, heat 3 tablespoons extra-virgin olive oil in Dutch oven over medium heat until shimmering. Add 2 finely chopped onions and ¼ teaspoon table salt and cook, stirring occasionally, until dark golden brown, adjusting heat as needed if beginning to scorch, 10 to 15 minutes.
Transfer onions to blender jar along with 1 cored and coarsely chopped tomato and process on low speed until coarse puree forms, about 1 minute. Scrape down sides of blender jar, then process on high speed until sauce is completely smooth, about 1 minute.
Pat dry 4 chicken breasts, trimmed and cut into 1½-inch pieces, with paper towels and sprinkle with 1 teaspoon salt. Heat remaining 2 tablespoons oil in now-empty pot over medium heat until shimmering. Add 3 whole cloves, 2 cinnamon sticks, and 2 bay leaves and cook, stirring occasionally, until fragrant, 30 to 60 seconds. Add 4 garlic cloves, minced to paste; 1 teaspoon grated ginger; 1 teaspoon ground coriander; 1 teaspoon ground turmeric; ½ teaspoon pepper; ¼ teaspoon ground cardamom; and ¼ teaspoon cayenne pepper and cook until fragrant, 30 to 60 seconds. Add cashew-onion mixture, ¾ cup tap water, and remaining ¼ teaspoon salt and stir, scraping up any brown bits from bottom of pot. Bring to simmer, then reduce heat to low, cover, and simmer gently for 10 minutes.
Stir in chicken, increase heat to medium, and return to simmer. Reduce heat to medium-low, cover, and simmer gently until chicken registers 160 degrees, 10 to 15 minutes. Discard bay leaves and cinnamon. Sprinkle korma with 1 cup coarsely chopped cilantro leaves and tender stems and 2 tablespoons chopped cashews and serve with plain yogurt.