Heat oil in large, deep frying pan over a medium-high heat. Add chicken. Cook, turning occasionally, for 5-6 minutes, until light golden. Remove from pan. Set aside.
Add onion, mushrooms and capsicum to same pan. Cook, stirring, for about 3 minutes or until lightly browned. Add tomato paste and garlic. Cook, stirring, for a further 1 minute.
Return chicken to pan. Stir in tomatoes, stock, olives and herbs. Bring to the boil. Reduce heat and simmer for about 15 minutes or until sauce has thickened. Transfer to an ovenproof pie dish (8-cup capacity).
For topping, brush bread slices with olive oil, then place over chicken mixture, overlapping slightly. Sprinkle with parmesan.
Bake in a 200 °C preheated oven for 12-15 minutes until topping is golden. Serve with salad leaves.