Steep the crushed garlic clove for the croutons in the olive oil.
Pre-heat the oven to 200°C.
Combine the beef mince, egg, breadcrumbs, dried thyme and seasoning in a large mixing bowl and mix with your hands until you have an even mixture. Line a baking tray with nonstick baking paper, then take generous tablespoons of the beef mixture and roll between your palms to make round meatballs. Arrange on the the lined baking tray, cover and chill until later.
Heat the olive oil in a large, heavy-based saucepan over a medium heat. Sweat the onion, carrot and celery for 7-8 minutes, stirring occasionally, until softened. Add the tomatoes, bay leaf, rosemary sprig and sugar and stir to mix well. Cover with a lid, reduce the heat to low and let the tomatoes and vegetables cook for 8-10 minutes, stirring every now and then.
Remove the lid, pour in the stock and bring to the boil over a moderate heat, then reduce to a simmer for 20 minutes.
Meanwhile, bake the prepared meatballs for 12-15 minutes until cooked. Turn the oven off once cooked, open the door, but leave the meatballs inside the oven. Remove the soup from the heat and discard the bay leaf and rosemary sprig. Puree using a stick blender until smooth, then adjust the seasoning as necessary. Keep the soup warm over a very low heat as you pre-heat the grill for the croutons.
Brush the baguette slices with the infused olive oil, then toast under the grill for 2 minutes on each side. Remove and sprinkle the Parmesan evenly on top. Grill for another 1-2 minutes until the cheese is melted, then remove.
Ladle the soup into soup bowls and dot with a few meatballs. Serve with the croutons on the side and season the top of the soup before serving. Garnish with a little basil, if available.
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For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.