TikTok baked spaghetti

Name: TikTok baked spaghetti
Ingredients: 1 tbsp olive oil; 1 medium onion, finely chopped; 1 garlic clove, crushed; 1 medium carrot, peeled and finely grated; 500g/1lb 2oz beef mince; 1 tbsp tomato purée; 2 tbsp Worcestershire sauce; 400g tin chopped tomatoes; pinch sugar (optional); 120g/4¼oz grated mozzarella; sea salt and cracked black pepper; 25g/1oz salted butter; 2 large garlic cloves, crushed; 1 tbsp dried mixed herbs; 300ml/½ pint double cream; 75g/2¾oz Parmesan, finely grated; 350g/12oz dried spaghetti