Karina's Chicken Tikka Masala

Name: Karina's Chicken Tikka Masala
Cuisine: Asian, Indian
Ingredients: 28 oz (800g) boneless and skinless chicken thighs (cut into bite-sized pieces); 1 cup plain yogurt; 1 1/2 tablespoons minced garlic; 1 tablespoon ginger; 2 teaspoons garam masala; 1 teaspoon turmeric; 1 teaspoon ground cumin; 1 teaspoon Kashmiri chili ((or 1/2 teaspoon ground red chili powder)); 1 teaspoon of salt; 2 tablespoons of vegetable/canola oil; 2 tablespoons butter; 2 small onions ((or 1 large onion) finely diced); 1 1/2 tablespoons garlic (finely grated); 1 tablespoon ginger (finely grated); 1 1/2 teaspoons garam masala; 1 1/2 teaspoons ground cumin; 1 teaspoon turmeric powder; 1 teaspoon ground coriander; 14 oz (400g) tomato puree ((tomato sauce/Passata)); 1 teaspoon Kashmiri chili ((optional for colour and flavour)); 1 teaspoon ground red chili powder ((adjust to your taste preference)); 1 teaspoon salt; 1 1/4 cups of heavy or thickened cream ((use evaporated milk for lower calories)); 1 teaspoon brown sugar; 1/4 cup water (if needed); 4 tablespoons Fresh cilantro or coriander (to garnish)