In a large bowl, whisk together Greek yogurt, garam masala, smoked paprika, ground cumin, minced garlic, ginger, and salt. Add the chicken thighs and coat well. Marinate in the refrigerator for at least 1 hour.

Heat a skillet over medium-high and add oil. Once hot, add marinated chicken, searing until golden brown on all sides (about 5-7 minutes). Set aside.

In the same skillet, reduce heat to medium, add onions and sauté until soft and golden (5-6 minutes). Stir in minced garlic, ginger, ground cumin, and smoked paprika; cook for 1 minute.

Pour in the tomato puree and simmer for about 10 minutes until slightly thickened.

Blend the sauce until smooth and then return to the skillet. Fold in heavy cream and simmer on low for 5 minutes.

Return seared chicken to the sauce, simmer on low for approximately 15 minutes until chicken is cooked through and flavors meld. Watch carefully to avoid sticking.

Garnish with chopped cilantro and serve hot with basmati rice or naan.