Preheat oven to 400°.
Whisk together first five ingredients; cut in butter until mixture resembles coarse crumbs.
In another bowl, whisk together egg, buttermilk and vanilla; stir into crumb mixture just until moistened. Stir in chocolate chips and hazelnuts.
Turn onto a lightly floured surface; knead gently eight times. Pat dough into a 6-inch circle. Cut into eight wedges; place on a greased baking sheet. Bake until golden brown, 15-20 minutes. Serve warm.