Marinate the chicken: In a mixing bowl, combine chicken pieces with salt, garlic powder, sweet paprika, curry powder, and Greek yogurt. Mix well, cover, and let marinate for at least 30 minutes, or refrigerate overnight for deeper flavor.

Cook the chicken: In a large skillet over medium-high heat, heat the vegetable oil. Add the marinated chicken pieces in a single layer, cooking until they’re browned on all sides, about 5-7 minutes. Remove and set aside.

Prepare the sauce base: In the same skillet, lower the heat to medium. Add 2 tablespoons of butter, garlic, and diced onion, cooking until soft and translucent, around 3-4 minutes.

Build the sauce: Pour in the tomato sauce, sugar, 1 teaspoon of salt, black pepper, and optional cayenne pepper. Stir to combine and simmer for 5 minutes, allowing the flavors to meld.

Season and simmer: Add the cooked chicken back to the skillet and stir in the heavy cream, garam masala, and additional curry powder. Simmer on low for another 10-15 minutes until everything is well-coated and the sauce thickens slightly.

Finish with butter: Stir in the remaining tablespoon of butter until melted and incorporated, adding a lovely richness to the dish.

Serve and enjoy: Garnish with chopped parsley if desired. Serve hot with naan bread and steamed rice for a complete meal.