Heat oil in a large frying pan over a medium-high heat. Add onion, garlic, carrot, celery and bacon. Cook, stirring, for 5 minutes, or until softened. Add minces, cook, stirring, until browned. Add wine, cook, stirring, for about 20 minutes. Add tomato paste, chopped tomatoes and simmer, uncovered, for 2 hours or until very thick. Season well with salt and freshly ground black pepper.

To make cheese sauce, melt butter in a medium size saucepan over a medium heat. Add flour, cook, stirring, for 1 minute, or until mixture thickens and bubbles. Gradually add milk, stirring constantly. Cook, stirring, until mixture boils and thickens. Stir in nutmeg and parmesan.

Preheat oven to 200°C (180°C fan-forced). Spoon mince mixture into a large, shallow, overproof dish. Slice zucchini lengthways. Arrange zucchini slices, overlapping slightly, over mince mixture, then spread the cheese sauce over the top. Sprinkle with mozzarella.

Bake for 40 minutes, or until browned. Serve.