In a mixing bowl, combine the yogurt with the lemon juice and zest. Toss in chicken pieces and marinate for an hour in the fridge.
Once chicken has had time to marinate, add 2 tablespoons butter into an ovenproof skillet over medium-high heat, then add in fresh ginger, garam masala, cumin, turmeric, and coriander. Stir until fragrant.
Add in the sliced onion and saute until translucent, then add in the diced tomatoes and the chicken and yogurt mixture.
Mix everything in pan over medium high heat until well combined, then add in 4 more tablespoons of butter. Place skillet in oven and cook until the chicken has reached an internal temp of 165F, about 15-20 minutes.
Top with fresh cilantro and serve with rice and naan bread.