In a ovenproof dish over moderate heat, drizzle 1 tbsp of olive oil and add the onions, and crushed garlic cloves and cook until softened but not coloured.
Pour the tomatoes, balsamic vinegar and some of the oregano into the pan and cook over a gentle simmer for 5 - 8 minutes or until thick and glossy.
Take off the heat and stir in the shredded turkey to the sauce. Check the seasoning and top with mozzarella and a sprinkle of parmesan.
Transfer in the oven for 20 - 25 minutes or until the turkey is piping hot and the mozzarella caramelized.