For the chicken:
1-1/2 lbs boneless, skinless chicken breasts (3 to 4 breast halves total)
1/4 Cup plain whole-milk Greek-style yogurt
2 Tbsp peanut or grapeseed oil (or other oil with a high smoke point)
2 tsp fresh lime or lemon juice
1 large clove garlic, minced
For the sauce:
2 Tbsp Tikka Masala seasoning
1 Tbsp grated or finely minced peeled fresh ginger (about a 1-inch piece)
4 Tbsp (1/2 stick) unsalted butter
1 large white onion, finely chopped
1-1/2 cups canned tomato purée
3/4 Cup water
1/2 Cup heavy cream or half-and-half
1-1/4 tsp kosher salt
1/2 tsp freshly ground black pepper
1/2 Cup chopped fresh cilantro (plus extra for garnish)
Marinate the chicken breasts
Poke the chicken breasts with a fork, all over on both sides, so they can “soak up” the marinade. Arrange the chicken breasts on a large sheet of plastic wrap or waxed paper, so that they are not touching one another, then cover with a second large sheet of plastic wrap (or waxed paper). Using the smooth side of a meat mallet or a rolling pin, beat the chicken until the breasts are an even 1/2- to 3/4-inch thickness.
In a shallow dish, whisk together the whole-milk yogurt, 1 Tbsp of the grapeseed or peanut oil, fresh lime or lemon juice, and garlic. Add the pounded chicken to the dish, and lightly toss or rub the marinade so that the meat is thoroughly coated. Set aside.
Make the sauce:
In a small bowl, toss together the Tikka Masala spices and grated fresh ginger. Over medium-high heat, melt the butter in a heavy, wide pot, Dutch oven or deep sauté pan. Add the chopped onion and sauté, stirring occasionally, until pieces are light brown and caramelized, about 6 – 8 min, being careful to stir often and not over-brown.
Reduce the heat to medium add the spice and ginger mixture to the onions, stirring to coat the onion and to “toast” the spices a little. Add the tomato purée, water, heavy cream, and salt, and bring the sauce to a boil. As soon as the mixture boils, reduce the heat to a gentle simmer. Allow the mixture to simmer, uncovered, for about 15 minutes, or until the sauce has thickened a little bit.
While sauce is simmering, cook the marinated chicken:
Heat a large (11 or 12″) heavy skillet over medium-high heat, adding the remaining 1 Tbsp of peanut or grapeseed oil. Working in batches, cook the chicken breasts, turning them a few times to brown all sides, and adjusting the heat if the chicken sticks or browns too quickly. Cook chicken until just cooked through and well-browned all over, only 6 to 8 minutes total. Transfer the cooked chicken to a cutting board. Allow chicken to cool slightly on the cutting board before handling.
Cut cooked chicken breasts into “bite-sized,” 1-1/2″ pieces. Add the pieces of chopped chicken to the simmering tomato cream sauce, continuing to simmer gently, stirring occasionally, to coat the chicken with sauce and heat it thoroughly. Remove the pan from the stove, stir in the ground black pepper and chopped fresh cilantro. Adjust seasoning, if necessary, season with salt.
Transfer the chicken to a serving dish and garnish with optional cilantro sprigs. Serve immediately with naan, and/or if desired, serve on a bed of Basmati Rice.
Make ahead: The spiced tomato cream sauce can be prepared ahead, then cooled, covered and refrigerated, in an airtight container, up to 3 days.