Preheat oven to 375 degrees F (190 degrees C). Line a baking sheet with parchment paper.
Whisk flour, white sugar, baking powder, lemon zest, and salt together in a large bowl. Cut unsalted butter into flour mixture with a knife or pastry blender until the mixture resembles coarse crumbs. Add cranberries and hazelnuts.
Beat 2 eggs and buttermilk together with a fork in a small bowl; add egg mixture to flour mixture and mix until the dough starts to come together and is just moistened. Let dough rest for 10 minutes.
Turn dough out on a lightly-floured surface and pat dough into a 1-inch thick circle. Cut circle in half with a sharp knife and cut each half into four sections. Gently transfer each section with a floured spatula to the prepared baking sheet.
Whisk 1 egg and cream together in a small bowl. Brush egg-cream mixture over each scone.
Bake in the preheated oven until the scones are golden brown and sound hollow when tapped, about 30 minutes. Remove to a wire rack.
Stir confectioners' sugar and lemon juice together in a bowl until desired glaze consistency is reached. Drizzle glaze over warm scones.
