In a mixing bowl, combine chicken thighs with salt, garlic powder, sweet paprika, curry powder, and Greek yogurt. Toss well to coat the chicken evenly. Cover and allow it to marinate for at least 15 minutes at room temperature.

Heat a large skillet over medium-high heat and add vegetable oil. Once shimmering, add the marinated chicken, cooking for 8-10 minutes.

Lower the heat to medium and add butter to the same skillet. Allow it to melt before adding minced garlic and diced onion. Sauté for 3-5 minutes until the onion is translucent.

Stir in the tomato sauce and sugar, let it simmer for 2-3 minutes, then return the cooked chicken to the skillet.

Add in the heavy cream, cayenne pepper, garam masala, and black pepper. Reduce heat to low and simmer for 10 minutes.

Stir in the remaining butter until melted for a rich finish. Taste and adjust any seasonings.

Serve the creamy sauce and tender chicken hot with naan and steamed rice.