In a medium bowl, combine skinless boneless chicken thighs with salt, garlic powder, sweet paprika, curry powder, and Greek yogurt. Let marinate for at least 15 minutes.

Heat vegetable oil in a large skillet over medium-high heat. Add the marinated chicken thighs and cook for 8-10 minutes until golden brown, then set aside.

In the same skillet, melt butter and sauté minced garlic and chopped onion until onions become translucent.

Stir in tomato sauce and sugar, allowing to simmer for 3-5 minutes until thickened.

Return the chicken to the skillet, add heavy cream, and stir until the sauce is creamy and heated through.

Add cayenne pepper, garam masala, and black pepper. Simmer for about 10 minutes, adjusting spice levels.

Stir in remaining butter at the end for a silkier sauce. Garnish with parsley if desired.

Serve hot with naan bread and steamed rice.