Bake the chicken: Transfer the marinated chicken to a baking tray, and brush with olive oil. Bake at 400℉ for 10 minutes. You can start on the sauce while it is baking. When the timer goes off, remove and set aside.
While waiting for the chicken to bake, make the sauce. Heat a cast-iron pan on medium heat and add in the following ingredients successively: onion, butter, tomato paste, 2 teaspoons of garlic powder, and 1/2 teaspoon of ginger powder. Stir around for a minute.
Continue to add to the pan: green bell pepper, 1/2 teaspoon of cinnamon, 1 teaspoon of cumin powder, garam masala, 2 teaspoons of paprika, 1/2 teaspoon of salt, 1/4 teaspoon of ground black pepper, and 2 teaspoons of coriander powder. Stir them around for a minute.
Next, add tomato sauce and water to the pan, let it simmer for 3 minutes, stir frequently.
Add the baked chicken chunks into the pan, mix together with the sauce. Let simmer for 3 minutes.
Lastly, pour heavy cream and coconut milk into the pan, whisk them well to combine with the rest.
Sprinkle fresh chopped coriander on top and serve immediately with hot steamed rice.