Place kecap manis mixture, chicken and chestnuts into a large snap lock plastic bag. Toss to coat chicken and chestnuts in mixture. Seal and refrigerate for 1 hour (or longer if time permits).
Preheat oven to 220°C/200°C fan-forced. Transfer chicken and chestnut mixture to a large baking pan lined with non-stick baking paper. Roast, turning occasionally, for 30-35 minutes or until chicken is golden and cooked through in the thickest part.
Remove from oven, sprinkle with coriander. Serve with steamed rice and Asian greens.
*kecap manis is a sweet soy sauce available in the Asian grocers section of supermarkets or from speciality Asian grocers.