Remove skin, score chicken, pat dry, season with lemon and salt, and let sit for 10 minutes.
Whisk yogurt, ginger-garlic paste, remaining lemon juice, spices, kasuri methi, oil, and optional food coloring until smooth.
Coat chicken thoroughly with marinade, work into slashes, cover, and refrigerate for at least 4 hours (overnight preferred).
Preheat oven to 450°F (230°C) with rack in top third. Line a baking sheet with foil, place a wire rack on top, and oil the rack.
Arrange chicken on the rack and roast for 20 minutes. Flip and cook for another 12-15 minutes until internal temperature reaches 165°F (74°C).
Brush chicken with melted butter, lemon juice, and chaat masala during the last 5 minutes of cooking. Rest for 5 minutes.
Garnish with lemon wedges, sliced onions, and cilantro. Serve with mint chutney, naan, or rice.