Preheat oven to moderate 180˚C. Place the chillies, fennel, cumin, coriander seeds and salt in a small food processor or mortar and pestle and process/grind until the spices are blended to a powder.
Remove any excess fat from the chicken and rub the skin and inside cavity with the crushed garlic.
Heat the oil in a wok, add the onion and cook over medium heat for a couple of minutes, until golden. Add the pork mince and cook for 10 minutes or until the pork is brown. Remove from heat, stir in the peanuts, lime juice, mint and coriander. Allow to cool slightly.
Stuff the chicken with the pork mixture. Tightly secure the opening with a wooden skewer and tie the legs together with some kitchen string.
Brush the outside of the chicken lightly with oil and then rub the skin with the ground spice mixture. Place the chicken on a rack in a baking dish. Bake for 30 minutes. Remove the chicken from the oven and baste with the coconut milk and pan juices. Bake for another 40 minutes, basting frequently until the chicken is tender. Remove skewer and string before serving.
Use the leftover chicken from the roast in soup or fried rice.