Simmer the potatoes, chicken, and sauce. Transfer the spiced potatoes, marinated chicken, and any remaining marinade in the bowl to the Dutch oven. Add 1 cup water, stir to combine, and bring to a simmer. Simmer uncovered, stirring occasionally, until a creamy sauce forms, about 20 minutes. Meanwhile, arrange a rack in the middle of the oven and heat the oven to 400°F.