Add cashew nuts to a food processor, and lightly pulse to chop
Add all spices, tomato paste, and garlic to the food processor, along with 3 tablespoons of water, and pulse to combine. It should form a paste.
Transfer paste to a medium bowl, add the Greek yogurt, and stir to combine.
Add chopped, uncooked chicken to bowl, and stir until all of the chicken has been coated in the sauce.
Refrigerate for 1 hour, or up to 24 hours. (If you are short on time, you can skip this step, and the results will still taste great!)
Once you are ready to cook, heat the oil in a skillet. Cook the peppers and onions for 5 minutes until peppers are soft and onion is translucent.
Add in the chicken and marinade, as well as the ½ cup chicken stock. Cook over medium heat for 15 minutes, stirring occasionally.
Add the heavy cream, reduce heat to low, and simmer for an additional 10 minutes.
Serve over cooked basmati rice.