Preheat oven to 180°c. Line a baking tray with baking paper.
Cook potatoes in a large saucepan of boiling water for 20 minutes or until very tender but not falling apart. Drain well, return to hot saucepan and slowly add milk and broccoli powder. Beat mixture with a wooden spoon until well combined. Stir in cheese and nutmeg. Set aside and keep warm.
Lay chicken breast down and slice it in half horizontally, separating top from bottom. Coat in oregano and garlic and season with pepper to taste.
Place oil in a large non-stick frying pan over medium-high heat. Add chicken halves and cook for 1-2 minutes each side or until browned. Transfer to prepared tray.
Place flatbread strips on tray alongside chicken and bake for 10 minutes or until chicken is cooked through and flatbread crisp. Serve chicken with mash, flatbread crisps, yoghurt and cherry tomatoes.