Place all ingredients except the cilantro and scallions in a large heavy-bottomed saucepan or Dutch oven and bring to a boil over medium-high heat. Reduce the heat to medium low and cook at a lively simmer, stirring occasionally, until the rice has completely broken down and the mixture is creamy, about 1 hour.
Turn off the heat and remove the chicken to a cutting board. When it’s cool enough to handle, shred the chicken into bite-sized pieces, discarding the cartilage and bones. Return the chicken shreds to the jook. Stir to combine, taste, and season with additional salt and pepper as needed.
Ladle into bowls and top with cilantro and scallions.