In a large mixing bowl, combine the chicken pieces, plain yogurt, and half of the tikka masala paste. Mix well to ensure all the chicken is coated. Cover the bowl and let it marinate for at least 30 minutes, or refrigerate for up to 2 hours for deeper flavor.
In a large skillet or Dutch oven, heat the olive oil over medium heat. Add the chopped onion and sauté until it becomes translucent and slightly golden, about 5-7 minutes.
Once the onions are ready, add the minced garlic, chopped chili, and curry leaves to the skillet. Sauté for an additional 2-3 minutes until fragrant.
Add the marinated chicken along with the remaining tikka masala paste to the skillet. Stir well to combine and cook for about 5-7 minutes until the chicken is browned on all sides.
Pour in the chicken broth, canned diced tomatoes, and tomato paste. Stir everything together, scraping any browned bits from the bottom of the pan. Bring the mixture to a simmer.
Reduce the heat to low, cover the skillet, and let the Chicken Masala simmer for 20-25 minutes. This allows the flavors to meld and the chicken to become tender.
Once the chicken is cooked through, stir in the heavy cream. Allow it to simmer for an additional 5 minutes, letting the sauce thicken slightly. Taste and adjust seasoning if necessary.
Serve your Chicken Masala hot, garnished with fresh cilantro if desired. Pair it with naan, rice, or your favorite side dishes for a complete meal.