Preheat oven to 400◦F.
Mix flour, 1/3 cup sugar, baking powder, baking soda, and salt in a large bowl.
Add butter.
Combine dry ingredients using a pastry blender (or two forks) until butter is reduced to the size of grains of rice.
Add walnuts and cranberries to flour mixture, tossing gently.
Whisk buttermilk, egg yolk, and vanilla in a 2-cup liquid measuring cup or small bowl.
Gradually add liquids to dry ingredients; mix until dough forms a ball. (You may not need to use all of the liquids.)
Place dough on a lightly floured surface and press into an 8-inch round.
Cut into 8 wedges. Sprinkle with 2 tablespoons sugar.
Transfer wedges to rimmed cookie sheet, preferably lined with parchment paper.
Bake for 15-20 minutes or until the scones are crusty on top and a tester inserted into the center comes out clean.
Serve warm.