1.Preheat oven to 220°C (200°C fan forced).
2.Meanwhile, spray a large saucepan with oil, add onion, carrot, celery and garlic. Cook on stove top, stirring over high heat, for 5 minutes or until onion softens.
3.Add beef, cook, stirring, for 5 minutes. Add tomato and sauce, reduce to a simmer. Simmer, stirring occasionally, for 15 minutes or until beef mixture thickens. Season to taste.
4.Meanwhile, cook potato and pumpkin in a large saucepan of boiling water for 15 minutes or until tender, drain. Return to pan, mash until smooth. Add cream cheese, stir to combine, season to taste.
5.Spoon beef mixture into a 4-cup (1-litre) ovenproof pan. Top with pumpkin mash.
6.Bake for 10 minutes or until heated through. Sprinkle with chives, and serve with rocket leaves.