In a bowl, combine the chicken pieces with yogurt, ginger-garlic paste, garam masala, turmeric, red chili powder, and salt. Mix well and let it marinate for at least 30 minutes.

Heat oil in a large skillet over medium heat. Add the marinated chicken and cook until browned and cooked through, about 10-12 minutes. Remove chicken and set aside.

In the same skillet, add chopped onion and sauté until translucent. Add butternut squash and cook for 5 minutes.

Pour in coconut milk and chicken broth. Bring to a simmer and cook until squash is tender, about 15 minutes.

Blend the mixture until smooth using a blender.

Return the blended sauce to the skillet, add the cooked chicken, butter, coriander, cumin, and black pepper. Stir well and simmer for 5 minutes.

Adjust seasoning if necessary. Serve hot, garnished with lime juice and cilantro.