Slice the squid tubes 1cm thick and pat dry with kitchen paper, set aside. Pour the stock into a saucepan, heat the oil and gently sauté the shallots about 5 mins or until soft and lightly coloured. Add the rice and cook over a medium heat for 2-3 minutes stirring frequently. Pour in the wine and stir until absorbed. Ladle in a quarter of the stick and cook. Keep adding stock a little at a time and cook for about 12 minutes or until the rice grains are plump and creamy. In a sauté pan, heat the oil and quickly stir fry the squid for 2-3 minutes. Remove with a slotted spoon, stir in the shallots and sauté for 5 mins. Add the vinegar and cook until reduced by half. Whisk in the butter until it melts and the sauce is glossy. Return the squid to the pan and season. Fold in the risotto with the mascarpone and parmesan. Season to taste, stir well and serve.