In a bowl, toss the chicken with salt, garlic powder, paprika, curry powder, and Greek yogurt. Mix until evenly coated and let sit for 10–15 minutes while you prep the rest.

Heat vegetable oil in a large skillet over medium-high heat. Add chicken in a single layer (work in batches to avoid crowding). Sear until golden, about 4–5 minutes per batch. Transfer seared chicken to a plate and set aside.

Reduce heat to medium. Add 2 tablespoons of butter to the same skillet and let it melt. Add the diced onion and sauté until soft and translucent, about 4–5 minutes. Add minced garlic and cook for 30–45 seconds until fragrant.

Stir in the tomato sauce, sugar, salt, and black pepper. Let the sauce come to a gentle simmer for 3–4 minutes to let the flavors meld.

Stir in the heavy cream and cayenne pepper if using. Return the chicken and any juices to the skillet. Sprinkle in garam masala and the additional curry powder.

Reduce heat to medium-low and simmer for 6–8 minutes, until the chicken is cooked through (internal temp 165°F/74°C) and the sauce has slightly thickened.

Swirl in the remaining tablespoon of butter for shine and richness. Taste and adjust salt, sugar, or cayenne as needed. Garnish with chopped parsley and serve hot with steamed rice and warm naan.