Step 1Preheat oven to 160°C. Lightly spray a 1.5L (6-cup) capacity ovenproof dish with olive oil. Combine mince, parsley, carrot and zest in a large bowl. Shape 12 large meatballs (approximately 2 tablespoons each) from the mince mixture.
Step 2Spray a large non-stick frying pan with oil and set over high heat. Cook the meatballs for 3–4 minutes, turning, until golden. Transfer to baking dish; meatballs will not be cooked through yet.
Step 3Return same pan to medium heat, spray with a little more oil. Sauté onion for 5 minutes, or until softened. Add garlic and cook, stirring, for a further 1 minute. Add tomatoes, zucchini, olives and 1/2 cup of water, and bring pan to the boil. Reduce heat and simmer for 8–10 minutes, or until thick. Carefully pour tomato mixture over meatballs, dot top with ricotta. Bake for 20 minutes, or until sauce is bubbling.
Step 4Meanwhile, boil potatoes for about 15 minutes, or until tender. Drain, return to saucepan with milk, and mash until smooth. Serve meatballs with mash and steamed broccolini.