Stuffed marrow

Name: Stuffed marrow
Ingredients: 1 medium marrow, cut in half widthways; 5 garlic cloves; 3 tbsp chopped fresh thyme; 3 tbsp olive oil, plus extra for brushing the marrow; 2 large onions, roughly chopped; 500g/1lb 2oz beef mince; 2 tbsp tomato purée; 2 tbsp sun-dried tomato paste (or 2 tbsp chopped sundried tomatoes); 450g/1lb fresh tomatoes (or 1 x 400g/14oz can chopped tomatoes); 3 tbsp finely chopped fresh parsley, plus extra for serving; 3 free-range eggs, beaten; 75g/2¼oz parmesan, grated, plus extra for serving; 75g pecorino, grated; Salt and freshly ground black pepper