In a large bowl, combine chicken cubes with yogurt, lemon juice, ginger-garlic paste, garam masala, turmeric powder, Kashmiri red chili powder, ground cumin, ground coriander, and salt. Mix well to ensure chicken is evenly coated.

Cover the bowl and refrigerate for a minimum of 30 minutes, or ideally 4 hours, up to overnight, to allow flavors to meld. (This time is not included in active prep time).

Preheat your cooking appliance: For oven, preheat to 400°F (200°C). For air fryer, preheat to 375°F (190°C). For grill, preheat to medium-high heat.

Thread the marinated chicken pieces onto skewers, leaving a small space between each piece. (If using oven/air fryer without skewers, arrange on a baking sheet/air fryer basket in a single layer).

Oven/Air Fryer: Bake/air fry for 15-20 minutes, flipping halfway, until chicken is cooked through and lightly charred at the edges. Internal temperature should reach 165°F (74°C). Grill: Grill for 8-12 minutes, turning occasionally, until chicken is cooked through and has nice char marks.

Set the cooked chicken aside.

In a large, heavy-bottomed pot or Dutch oven, heat ghee or oil over medium heat.

Add finely chopped onion and sauté for 8-10 minutes, stirring occasionally, until deeply golden brown and softened. Do not rush this step, as the caramelized onions contribute significantly to the sauce's flavor.

Add ginger-garlic paste and green chilies (if using) and sauté for another 1-2 minutes until fragrant.

Reduce heat to low. Add garam masala, ground cumin, ground coriander, turmeric powder, and Kashmiri red chili powder. Stir constantly for 30 seconds to 1 minute until fragrant, being careful not to burn the spices.

Stir in the crushed tomatoes and tomato paste. Add the drained soaked cashews, salt, and sugar. Increase heat to medium-low and bring to a gentle simmer.

Cover and cook for 15-20 minutes, stirring occasionally, allowing the flavors to meld and the tomatoes to break down.

Carefully transfer the sauce mixture to a blender (or use an immersion blender directly in the pot). Blend until completely smooth. If needed, add a small amount of water or chicken broth to achieve desired blending consistency.

Return the smooth sauce to the pot over medium-low heat.

Stir in the cooked chicken tikka pieces into the sauce.

Pour in the heavy cream and add the crushed Kasuri Methi. Stir gently to combine.

Simmer for another 5-10 minutes, allowing the chicken to heat through and the flavors to fully meld. If the sauce is too thick, add a little water or chicken broth until it reaches your desired consistency. Taste and adjust salt or sugar if necessary.

Garnish generously with fresh chopped cilantro before serving.