In a large bowl, combine chicken thighs with salt, garlic powder, curry powder, and Greek yogurt. Cover and marinate in the refrigerator for at least 15 minutes.

Heat vegetable oil in a skillet over medium-high heat. Add marinated chicken and cook for about 8 to 10 minutes until cooked through. Remove chicken and set aside.

In the same skillet, reduce heat and melt butter. Add garlic cloves and onion, sauté until translucent.

Stir in tomato sauce and sugar, simmer for 5 minutes. Return chicken to skillet, coating it with the sauce.

Reduce heat and stir in heavy cream, cayenne pepper, garam masala, and black pepper. Simmer for an additional 10 minutes.

Finish with a pat of butter and chopped parsley, serve warm.