Preheat oven to 200°C and line an oven tray with baking paper.
Toss kumara with olive oil and rosemary on lined oven tray and season with salt and pepper. Roast for about 15 minutes until golden turning once during cooking.
Pat chicken breasts dry with paper towels and cut horizontally into thin steaks; to do this, lay on hand flat on top of a chicken breast on a chopping board and use a large sharp knife in the other hand to carefully and evenly slice through horizontally, keeping equal thickness on either side as best you can. Season each piece with salt. Heat oil in a large fry-pan. Brown chicken steaks for 1 minute on each side (do not cook all the way through). Set aside.
Tip crushed tomatoes into fry-pan chicken was cooked in, stir in tomato paste, dried herbs and chilli flakes (if using), and simmer, stirring frequently, on medium heat for about 8 minutes or until sauce has thickened. Season to taste with salt and pepper and set aside.
Once kumara is cooked, transfer to a bowl, keep warm and switch oven to grill. Arrange eggplant on same lined tray, brush (or spray) lightly with olive oil and season with salt. Grill for 6-8 minutes, turning halfway through cooking until soft and lightly browned. Transfer to a plate (but keep lined tray).
Place chicken steaks on lined tray and top with eggplant slices, dividing equally. Spread with tomato sauce then sprinkle with mozzarella and Parmesan. Grill for 5-6 minutes or until chicken is cooked through and cheese is melted and bubbly.
Garnish parmigiana with basil and serve with roasted kumara and green salad or sauteed vegetables.