Step 1 Preheat oven to 160°C. Slice each chicken fillet horizontally through the centre to make 4 thin fillets. Set a large non-stick frying pan over high heat and spray with olive oil. Add chicken to pan and cook for 2 minutes per side, or until golden. Transfer chicken to a large baking dish.
Step 2 Put reserved tomato–eggplant sauce, chilli flakes, vinegar and capsicum in a large bowl; stir to combine. Spoon tomato mixture evenly over cooked chicken in dish. Place dish in oven to bake for 20 minutes, or until tomato mixture thickens and chicken is cooked through.
Step 3 Meanwhile, place chopped potatoes and cauliflower florets in a large saucepan of cold water; bring to the boil, then reduce heat and simmer for 15 minutes, or until vegetables are tender. Drain vegies well and return to saucepan. Add skim milk to pan and mash until smooth.
Step 4 Halve chicken fillets crossways. Divide chicken and cauliflower mash among serving plates. Spoon tomato mixture over chicken and scatter with parsley.
Step 5 Serve bake and cauliflower mash with green beans.