In a medium bowl, mix the chicken thighs with salt, garlic powder, sweet paprika, curry powder, and Greek yogurt. Cover and let it rest in the refrigerator for at least 15 minutes.

Heat vegetable oil in a large skillet over medium-high heat. Once hot, add the marinated chicken and cook for 8-10 minutes until golden brown. Remove the chicken and set aside.

Reduce heat to medium, add butter to the skillet to deglaze the pan, and add garlic and diced onion. Sauté until the onion is translucent.

Stir in the tomato sauce and sugar, allow to simmer for 3-4 minutes before returning the cooked chicken to the skillet.

Add cayenne pepper, garam masala, curry powder, and black pepper. Let everything simmer on low for about 10 minutes.

Stir in the heavy cream and cook for an additional 2-3 minutes until heated through.