In a medium bowl, combine the chicken pieces with salt, garlic powder, sweet paprika, curry powder, and Greek yogurt. Toss until evenly coated. Cover and refrigerate for at least 15 minutes; up to 2 hours for more tenderness.

Heat 2 tablespoons vegetable oil and 1 tablespoon butter in a large skillet over medium heat. Add minced garlic and diced onion. Sauté, stirring occasionally, until the onion is soft and translucent, about 4 to 5 minutes.

Stir in the tomato sauce, sugar, salt, black pepper, heavy cream, cayenne if using, garam masala, and the extra curry powder. Bring to a gentle simmer and cook for 3 to 4 minutes so the flavors marry. Keep the sauce on low heat while you cook the chicken.

In a separate heavy skillet, heat the remaining 1 tablespoon oil over medium-high heat. Add the marinated chicken pieces in a single layer; avoid crowding the pan. Cook without moving for 2 to 3 minutes to get good browning, then stir and cook another 3 to 4 minutes until pieces are browned and cooked through (internal temp 165°F / 74°C).

Transfer the cooked chicken to the sauce. Stir in the remaining 2 tablespoons butter until fully melted and glossy. Simmer everything together for 2 to 3 minutes to marry the flavors. Taste and adjust salt or cayenne. Garnish with chopped parsley if you like.

Spoon over steamed rice and pass warm naan.