How to make it
Mix oyster sauce with cornstarch, add chicken pieces and stir to coat. Set aside.
Preheat the oven to 190°C(375°F). Heat oil in a large ovenproof casserole, add onion and pancetta/bacon and cook over medium-low heat 5 minutes until softened. Increase heat, add chicken pieces, and cook, turning for 2–3 minutes. Add garlic and cook 1 additional minute.
Add remaining vegetables to casserole along with stock. Bring to simmer, stirring well. Cover and place in oven 30 minutes.
Cut potatoes into 0.6 cm slices. Increase oven temperature 200°C(400°F). Take hot casserole from oven, remove lid, and arrange potato slices over top. Brush with melted butter then cook for another 30-40 minutes, until potatoes are golden brown. Sprinkle with parsley before serving.