In a medium frying pan over low heat, toast cumin and coriander seeds until fragrant, 3 to 5 minutes. Transfer seeds to a spice grinder and process until finely ground. Zest lemons and set aside zest. Juice 1 lemon and set aside 3 tbsp. juice.
Melt butter in the frying pan over medium heat. Add ginger, jalapeño, and salt. Cook until jalapeño is soft, 3 to 5 minutes. Remove from heat and set aside.
In a large bowl, stir together mayonnaise, yogurt, lemon zest, lemon juice, ginger-jalapeño mixture, and ground spices. Add cilantro, green onions, and chicken; stir to coat well with dressing. Taste and adjust seasonings as needed. Sprinkle with cashews and serve.
Note: Nutritional analysis is per serving.