In a mixing bowl, combine Greek yogurt, lemon juice, ginger-garlic paste, and spices to form a marinade. Cut chicken into bite-sized pieces and coat thoroughly. Refrigerate for at least 1 hour, ideally overnight.

Heat a skillet over medium-high heat and add a splash of oil. Once hot, add marinated chicken pieces in batches and sear for 5-7 minutes or until golden-brown.

In the same skillet, melt butter or ghee. Add finely chopped onions and sauté for 5-6 minutes until golden. Stir in minced garlic and ginger, cooking for 1-2 minutes.

Mix in the tomato paste and crushed tomatoes. Allow sauce to simmer on low for about 10-15 minutes, stirring occasionally.

Gradually incorporate heavy cream or coconut milk. Stir constantly and season with salt, pepper, and sugar. Simmer for an additional 5 minutes.

Add the cooked chicken back into the skillet with the sauce and simmer for another 5 minutes to meld the flavors.

Squeeze fresh lemon juice over the dish and garnish with chopped cilantro. Serve with warm naan or basmati rice.