In a bowl, combine chicken, salt, garlic powder, sweet paprika, curry powder, and Greek yogurt. Mix well and marinate for at least 15 minutes.
Heat vegetable oil in a large skillet over medium-high heat. Add chicken and cook 8–10 minutes until fully cooked and lightly golden. Remove and set aside.
Reduce heat to medium and melt 1 tablespoon butter. Add garlic and onion with a pinch of salt. Sauté until softened and fragrant.
Stir in tomato sauce and sugar. Simmer 2–3 minutes, then return chicken to the skillet.
Pour in heavy cream and stir until smooth. Add cayenne (if using), garam masala, curry powder, and black pepper.
Simmer gently on low heat for 10 minutes, stirring occasionally. Adjust seasoning as needed.
Stir in remaining cold butter until fully melted and incorporated. Garnish with parsley if desired.
