Bring a medium pot of water to a rolling boil. Add half the spinach and press the leaves under the water. Cook for about 30 seconds, then lift the spinach out with a slotted spoon and drain it on a plate or in a bowl. Repeat with the remaining spinach.

In a bowl, combine the ground chicken, egg, breadcrumbs, and ¼ teaspoon salt. Scoop about 2 tablespoons of the mixture at a time and shape it into balls. Keep a small bowl of water nearby and dampen your hands before shaping each kofta to prevent sticking. If the mixture is too soft to shape, mix in up to 2 tablespoons more breadcrumbs.

Heat the vegetable oil in a large nonstick sauté pan over medium-high heat. When the oil is moderately hot, add the koftas in a single layer. Cook until golden on the bottom, gently turn, and brown the other side. The koftas will not be fully cooked yet. Transfer them to a plate with a slotted spoon, letting excess oil drain back into the pan.

Keep the pan over the same heat. Add the onion, garlic, ginger, and cashews, along with ½ teaspoon salt. Sauté until the onion is translucent and beginning to turn golden. Add the tomato, coriander, cayenne or chili powder, garam masala, and turmeric. Cook, stirring, until the mixture thickens and the oil begins to separate.

Remove the pan from the heat. Transfer its contents and the blanched spinach to a food processor. Process for about 2 minutes, just until ground; avoid blending the mixture completely smooth.

Return the blended mixture to the empty sauté pan. Add the browned koftas, 1 cup water, sugar, and the remaining salt to taste. Bring to a boil over medium heat, then cook for 3 to 5 minutes, until the chicken koftas are cooked through and the gravy has thickened. Remove from the heat and serve hot.