Preheat oven to 180ºC (355ºF). Place the sweet potato, half the parmesan, oil, salt and pepper in a bowl and toss until well combined. Layer the sweet potato on a baking tray lined with non-stick baking paper, sprinkle over the remaining parmesan and bake in the oven for 25 minutes or until golden.
Heat a large frying pan over high heat. Add the extra oil and chicken and cook for 3 minutes each side. Place on a baking tray and cook in the oven for 10 minutes or until cooked through. Add the stock, rosemary, mustard, salt and pepper to the frying pan and cook for 2 minutes. To serve, cut the sweet potato into squares, top with the spinach and chicken and spoon over the warm rosemary sauce. Serves 4.