1.Preheat oven to 200°C/180°C fan forced. Place pumpkin on a baking tray lined with baking paper. Sprinkle with rosemary and drizzle with half the oil. Bake, 25 minutes, or until golden and tender.
2.Meanwhile, heat remaining oil in a large, heavy-based flameproof and ovenproof dish over moderate heat. Add onion and garlic, cook and stir, 5 minutes, or until onion is soft.
3.Add rice, cook and stir, 1 minute, until rice is coated. Add wine, 3 1/2 cups water and crumbled stock cubes. Bring to boil.
4.Cover dish with foil, bake 18-20 minutes, or until liquid is almost absorbed, stirring chicken into rice during last 5 minutes.
5.Coarsely shred half the rocket, stir into risotto. Add 2/3 cup of the parmesan, half the zest and most of the pumpkin. Serve topped with remaining pumpkin, zest, parmesan, whole rocket leaves and lemon wedges, if you like.