In a large bowl, combine flour, sugar, baking powder, and salt, whisking well. Using a pastry blender, cut butter into flour mixture until it resembles coarse crumbs. Add hazelnuts, stirring to combine.
In a small bowl, combine cream,
¼ cup plus 2 tablespoons milk, and vanilla extract, whisking well. Add to flour mixture, stirring until mixture comes together. (If mixture seems dry, add more cream, 1 tablespoon at a time.) Working gently, bring mixture together with hands until a dough forms.
Turn out dough onto a lightly floured surface. Knead gently 4 to 5 times.
Using a rolling pin, roll dough to a 1-inch thickness. Using a 2-inch fluted square cutter, cut 10 scones from dough, rerolling scraps as necessary. Place scones 2 inches apart on prepared baking sheet.
Brush tops of scones with remaining 1 tablespoon milk.
Bake until edges of scones are golden brown and a wooden pick inserted in the centers comes out clean, approximately 20 minutes.