Bring the milk, sugar and vanilla beans to a bare simmer over low heat for 10 minutes to infuse vanilla flavor. Remove the bean pods and keep the milk hot.
Heat 2 tablespoons of the butter in a large saucepan over moderate heat. Stir in the rice and cook, stirring until the rice is hot, about 2 minutes. Begin adding the hot milk 1 cup at a time, stirring often and adding more milk when the previous addition has been absorbed. Adjust heat to maintain a nice simmer. It will take about 20 minutes for the rice to become creamy and al dente. It is possible you may not need all of the milk. Remove the risotto from the heat and stir in the remaining butter, and chopped chocolate. Sprinkle with chopped hazelnuts, shave white chocolate over the top and serve.