Preparation Steps

• Preheat oven to 375°F (190°C). In a food processor, pulse together flour, hazelnuts, butter, and powdered sugar until mixture resembles coarse crumbs. Add ice water and pulse until dough comes together.
• Press dough into a 9-inch tart pan with removable bottom. Prick bottom with a fork and bake for 15-20 minutes, or until golden brown. Let cool completely.
• For the filling, place chopped chocolate in a heatproof bowl. In a saucepan, heat heavy cream and butter until simmering. Pour over chocolate and let sit for 1 minute. Stir until smooth and glossy. Stir in vanilla extract.
• Pour filling into cooled tart shell. Refrigerate for at least 2 hours, or until set. Garnish with chopped toasted hazelnuts before serving.