Preheat oven to 350°. In a large bowl, beat cream cheese and sugar until smooth. Beat in mascarpone cheese, sour cream, lime juice and vanilla. Add eggs; beat on low speed just until blended. Pour into crust. Place on a baking sheet., Bake 30-35 minutes or until center is almost set. Cool 1 hour on a wire rack., Meanwhile, for topping, place chocolate chips in a small bowl. In a small saucepan, bring cream just to a boil. Pour over chips; stir with a whisk until smooth. Stir in vanilla. Cool to room temperature or until mixture thickens to a spreading consistency, stirring occasionally., Spread chocolate mixture over pie; refrigerate overnight. Just before serving, top with hazelnuts.