In a large bowl, combine yogurt, lemon juice, turmeric, garam masala, cumin, coriander, ginger, garlic, and salt. Add chicken pieces and stir to coat thoroughly. Cover and refrigerate for at least 2 hours, preferably overnight for the best flavor development.

Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper or aluminum foil.

Arrange the marinated chicken pieces on the prepared baking sheet, leaving space between each piece. Brush with 2 tablespoons of melted butter. Bake for 15-20 minutes until chicken is cooked through and edges begin to brown.

While chicken is baking, melt 4 tablespoons of butter in a large, deep skillet or Dutch oven over medium heat. Add the onions and sauté until soft and translucent, about 5 minutes.

Add garlic and ginger to the skillet and cook for 1-2 minutes until fragrant. Stir in cumin, garam masala, coriander, paprika, and cinnamon. Cook for another minute to toast the spices and release their flavors.

Pour in tomato sauce and tomato paste. Add chopped green chilies. Stir well and bring to a simmer. Reduce heat to medium-low and cook for 15 minutes, stirring occasionally, until sauce thickens slightly and oil begins to separate.

For an ultra-smooth restaurant-style sauce, carefully transfer the sauce to a blender and blend until smooth. Return to the pan. (Skip this step if you prefer some texture.)

Add the remaining butter and stir until melted. Reduce heat to low and stir in the heavy cream, honey, and salt to taste. Simmer gently for 5 minutes.

Add the baked chicken pieces (with any accumulated juices) to the sauce. If using, crush the dried fenugreek leaves between your palms and sprinkle into the sauce. Simmer for another 5-10 minutes to allow flavors to meld.

Stir in chopped cilantro. Taste and adjust seasoning if needed. If the sauce is too thick, add a splash of water or chicken broth to reach desired consistency.

Garnish with additional cilantro and serve hot with basmati rice, naan bread, or roti for a complete Indian feast.