In a large saucepan sauté onion, garlic, carrot, and celery in olive oil until softened.
Add mince and brown for 10 minutes. Spoon out any excess liquid.
Add tomato paste and stir.
Add tomatoes, stock/broth, rosemary, salt and pepper and bring to a boil.
Reduce to a simmer uncovered for 25 minutes or until liquid has reduced.
Meanwhile, pre-heat fan-forced oven to 200ºC.
Boil or steam sweet potato for 10 minutes or until tender. Drain well.
Mash sweet potato with a pinch of salt and pepper.
Add spinach to mince filling and stir.
Spoon mince into a large ovenproof baking dish.
Top with mashed sweet potato using a fork to spread evenly. Drizzle lightly with olive oil.
Cook in oven for 20-25 minutes or until sweet potato edges are golden.