Cut chicken fillets horizontally through the middle to give 4 thin steaks altogether. Combine oil, herbs and garlic on a large plate. Add chicken. Turn to coat in herb mixture.
Heat a large, ovenproof, non-stick frying pan over a medium-high heat. Add chicken. Cook for 2-3 minutes on each side, until lightly browned.
Pour passata around chicken in pan. Bring to a simmer. Simmer uncovered 2 minutes, until chicken is cooked.
Divide capsicum and olives evenly over chicken. Scatter with tomatoes. Top chicken with cheese slices.
Preheat oven grill to high. Place pan under preheated grill for about 2 minutes, or until cheese is melted and lightly browned. Transfer pan to a heatproof mat or wooden board. Take care (use oven mitts) as handle will be hot.
Meanwhile, boil, steam or microwave sweet potato and zucchini separately until tender. Serve with chicken.