In a mixing bowl, combine chicken thighs with salt, garlic powder, sweet paprika, curry powder, and Greek yogurt. Coat well and refrigerate for at least 15 minutes.

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

In the same skillet, reduce heat to medium, add butter, minced garlic, and diced onion. Sauté for 3-4 minutes until onion is translucent.

Stir in tomato sauce and sugar, let simmer for 2-3 minutes. Return cooked chicken to the skillet, ensuring it's covered by the sauce.

Mix in heavy cream, cayenne pepper, and garam masala. Simmer for 10 minutes until the sauce thickens.

Remove from heat and stir in a pat of cold butter for shine. Garnish with fresh parsley and serve with naan and rice.