Combine the yogurt, tomato paste, ginger-garlic paste, vinegar, paprika, oregano, cumin, red chili powder, black pepper, and salt in a large bowl. Add the chicken cubes and toss to coat thoroughly. Cover and refrigerate for at least 1 hour, up to 4 hours.

Heat 2 tablespoons of oil in a large frying pan over medium-high heat. Add the marinated chicken and sauté for 8 to 10 minutes until the liquid has fully evaporated and the chicken is cooked through with slightly browned edges. Cover and cook on low for 2 more minutes if needed.

In a small saucepan over low heat, melt the butter. Whisk in the flour and cook for 1 to 2 minutes, stirring constantly, until the roux is smooth and pale.

Add the milk gradually in a slow, steady stream while whisking continuously. Add the dried parsley, black pepper, and a pinch of salt. Cook over medium-low heat, stirring regularly, until the sauce thickens enough to coat the back of a spoon, about 3 to 5 minutes.

Pour the white sauce evenly over the cooked chicken in the frying pan, spooning it over every piece.

Scatter the shredded mozzarella and cheddar over the top along with fresh cilantro or parsley and red chili flakes if using.

Cover the pan with a lid and cook over low heat for 1 to 2 minutes until the cheese is fully melted and bubbly across the surface.

Serve immediately while the cheese is gooey. Spoon over garlic rice or serve with warm pita or naan bread.