Heat 1 tbs oil in a deep, ovenproof frying pan over high heat. Add onion, carrot and garlic and 1 tsp dried oregano. Cook, stirring occasionally, for 3 minutes or until softened.
Add the beef and remaining oil. Break up any lumps with a wooden spoon and cook for 3 minutes or until browned. Stir in tomato paste for 1 minute or until combined.
Stir in the pasta sauce. Cover and cook for 2 minutes. Gently stir in the zucchini spaghetti. Cook for a further 2 minutes, covered.. Remove the pan from heat.
Preheat the oven grill to high. Sprinkle bolognaise with remaining dried oregano and mozzarella. Grill for 2-3 minutes or until cheese is golden and melted. Top with fresh oregano.