Boil the rice in abundant salted water and in another pan boil the potatoes. Clean the prawns and the peppers and cut into equal size cubes. Season the prawns and peppers with extra virgin olive oil, and a little salt and pepper. Sieve the potatoes, add the apple purée, the Parmesan and lastly the butter, stir delicately with a wooden spoon until the mixture is soft and fluffy. When the rice is cooked (about 15 minutes) drain and lay out onto a large plate or work top and leave to cool. Season the rice with the cubed prawns and peppers. Put the rice mixture into four individual moulds. Serve the rice salad by turning the moulds upside down in the centre of a plate with some potato and apple purée at the side. Complete the dish with a drizzle of extra virgin olive oil.