Season the Chicken: Lightly season sliced chicken thighs with salt and set aside.
Cook the Aromatics: Heat olive oil and butter in a large skillet over medium heat. Add diced onion and shallots and cook for 4–5 minutes until softened. Add garlic and ginger and cook for another 1–2 minutes, stirring frequently.
Brown the Chicken: Add the chicken to the skillet and cook until lightly browned on all sides.
Build the Sauce: Stir in garam masala, chili powder, cinnamon, garlic powder, and tomato paste. Cook for 2–3 minutes to deepen the flavor.
Add Creaminess: Pour in heavy cream, lemon juice, and a pinch of sugar. Stir until everything is well combined.
Simmer: Reduce heat to low and let simmer for about 20 minutes until the sauce thickens and chicken is fully cooked. Taste and adjust salt as needed.
Serve: Garnish with fresh cilantro and serve hot with naan bread.