Sauté the leek in butter. Add the rice and let it brown. Pour the sparkling wine and let it evaporate. Cook the rice, adding the broth one ladle at a time. 5 minutes before the end of the cooking time, add the apples cut into cubes. 1 minute before the end of the cooking time, add the Gorgonzola, the whipped cream, the Parmesan cheese and 2EL of the Mostarda Purée of quince. Mix everything and add pepper. Put the lid on for 1 minute, then stir the risotto. Arrange in a serving dish with a sprig of fresh parsley and serve.