Stir in the butternut squash, chicken, coconut milk, apple cider vinegar, curry powder, and salt. Bring to a boil, skimming any foam that rises, then reduce to a simmer. Cook, stirring occasionally, until the chicken is cooked through to an internal temperature of 165˚, and the squash is tender, about 15-20 minutes. Stir in the cilantro. Taste and adjust seasonings, and serve.