Cut the chicken into bite-sized pieces.
Marinate with Greek yogurt, lemon juice, garlic, ginger, salt, and chili powder for 30 minutes.
Add butter to a pan and grill the marinated chicken.
Remove the chicken and sauté onion, garlic, and ginger in the same pan.
Add tomato purée and let it simmer.
Return the grilled chicken to the sauce and add ground spices such as garam masala and cumin.
Mix in heavy cream and butter, then bring to a gentle boil.