Cut chicken thigh meat into small cubes and place them into a metal mixing bowl or a glass food storage container.
Whisk together plain yogurt, lemon juice, ginger, garlic, and all the spices for the marinate.
Pour in the yogurt mix into the chicken and mix very well, so the chicken is evenly coated in the marinate.
Cover air-tight and refrigerate for a good 6-8 hours. (You can marinate it up to 12 hours.)
Cooking Butter Chicken:
Add a tablespoon of oil and butter to a large cooking pan or a skillet.
Scoop some chicken out of the marinade and into the pan (don't shake off the marinade.) Sauté the chicken in batches over medium to medium-high heat, until almost done. Keep the batches small so that the chicken is not over-crowded and covers only about half the pan's surface. Once chicken is seared, set is aside and cook another batch.
In the same pan, melt another tablespoon of butter, lower the heat to just below medium and cook onion and jalapeno pepper until completely softened.
Make a little well in the center of the pan, between the veggies, and add minced garlic and ginger. Stir and let is sauté for just a few seconds until fragrant.
Return all the chicken back to the pan and stir in tomato paste, tomato sauce, and seasoning. Stir well.
Add heavy whipping cream and mix well. Lower the heat to low and let it stew for about 15 more minutes.
Serve the chicken with steamed basmati or jasmine rice and na'an. Garnish with some fresh cilantro.